The Palm Centro made its debut in Fall 2007 as the smallest and lightest Palm OS based smartphone to date. It is the third new model from Palm this year after the Treo 755p and Treo 500v. Palm basically took all that's good about the 755p, and packed it into a much leaner and lighter body. The Centro brings a number of high end smartphone features including 3G wireless data and a full qwerty keyboard into the $99 range. Presently traditional smartphones only make up a miniscule 5% of the US market for mobile handsets, estimated to be around 8 million sold annually (IDC). Of course the number of smartphones sold is widely expected to climb, but Palm's hopes today are that the Centro's new looks and low price will help them to tap into and compete with the significantly larger "feature phone" market segment which is in the 160 million unit range in the US alone. The approach with the Cento is to appeal to a younger demographic by functioning as a personal communications device first. More than likely the fresh design and smaller form factor will appeal to new and first time smartphone users, who may have been put off by the bulk and business like reputation of previous devices. Design The Palm Centro is initially available in a choice of two colors from Sprint, onyx black and ruby red. The casing is a smooth plastic with silver trim accents that wrap around the sides, back and front buttons. The cases colors have a nice subtle sparkle finish to them when viewed up close. Overall the new design is a good refinement of the classic Treo form factor, though the Centro does have a much more plasticy feel to it than previous Palm devices. Palm still can't seem to make it much thinner, but the compactness and pleasantly symmetrical rounded design of the Centro provides a positively smaller impression.

Present along the top of the device is the ever convenient silent mode switch. On the top of the front is a small LED charge indicator and the ear-speaker along with the Sprint logo. The screen is followed below with a newly designed flat button array. Again the screen is sunken a few millimeters into the body of the device. Making the screen flush with the surface of the device (a la iPhone) would to a tremendous amount to make this a much more classier sleeker looking device. That said, the buttons are mostly flush against the surface and do lend a nicer, smooth look. The circular racetrack directional pad protrudes out a bit and hides a fittingly subtle Palm logo on the inside center selector.

The sides of the device are mostly smooth with the aforementioned chrome-ish silver band running around the perimeter. The left side contains the volume buttons and customizable side key, while the right consists of the now seldom used IR window and hidden memory card door. The memory card door is a bit of an unintuitive design peculiarity as you can't access it without first removing the rear battery cover (more on that later).

The bottom of the device has the 2.5mm headset jack, the "athena" multi-connector and power port and the mic inlet. An odd addition is a new lanyard loop. This is a small little post where you can attach a wrist strap or one of those "phone charms" that are so popular in Japan. Sony used to include one of these on each of their Clie PDA devices, however I don't think I've ever seen one of these on a Palm device before.

I have to give Palm poor marks for the rear of the device with the removable battery door being the primary culprit. Even when attached normally the door feels somewhat squishy and will exhibit a tendency to creak and flex when held tight. It is also a magnet for fingerprint smudge buildup with its glossy sheen. Sliding it off can be a real challenge as well as there is no specific point to apply pressure in order to create friction to disengage the cover. It can also be awkwardly difficult to get the door back on as it is not very intuitive how to reattach it properly. Normally this wouldn't be so much of an issue, but in order to access the memory card door and to reset the device you have to physically remove and replace the back cover.

The included stylus is one of the flimsiest I've ever seen included with a device. It's a good thing it's not used very often, as this one is only slightly thicker than a toothpick and easily gives to pressure. The Centro also continues the recent no reset button policy. One must simply disconnect the battery in order to reboot the Centro. The same procedures apply for hard resets, you have to remove and reinsert the battery while holding down the power button as the device restarts.

Centro Hardware

The Centro is powered by a 312 MHz Intel PXA270 XScale processor. This is the exact same chip found on all previous Palm OS Treo models since the Treo 650 was released in 2004. Palm must have made some positive changes to boost performance because the Centro feels slightly more responsive and snappy, compared with its predecessors. You can move around the OS with less lag and switching between apps actually feels a bit faster. This is most likely attributable to improvements made to the internal memory architecture and file system, however I can only speculate as Palm won't comment on any specifics regarding performance and says the Centro's internals are similar to recent Treo's. It also seems like stability has been addressed as well as the Centro did not spontaneously reboot on me through the course of my evaluation.

A 128 MB non-volitile (NVFS) chip is on board for program memory, of which about 68.8 MB is user-available for storage. CorePlayer reports the dynamic heap as 8097 kb. A microSD slot is present for memory expansion which can accommodate microSD cards up to 4 GB in size.

Display
The Cento has a 1.56" x 1.56" inch, 320 x 320 pixel TFT display that supports up to 65,000 colors. It's a nice screen and the smaller size isn't an impediment, it actually looks a lot sharper due to the increased pixel density. It's also plenty bright and is more than adequate for daily use when toned down to about 50% on the brightness slider. The screen does tend to wash out a bit in bright, direct sunlight, but is still readable. My hat goes off to whoever figured out or thought to remove the useless 2 pixel white border that commonly surrounds the displays on Palm OS devices. This is actually the first color Palm OS device I've seen that does away with this odd border artifact.

Keyboard
Palm calls the Centro one of the slimmest candy bar form-factor phones with a full qwerty keyboard. In order obtain the smaller size the keyboard area and keys had to be condensed. The spaced out smile arrangement has been reworked into a miniature linear grid of clear bubbly like domes. Not only are the keys smaller, but they are packed in much more tightly as well, only a fraction of a millimeter apart.

Despite the smaller size and arrangement, the keyboard is still quite usable, but requires adjustment. I wouldn't call it a deal-breaker, however I definitely found myself making more mistakes and typos than usual, but I improved over time. The Centro does work well for the quick IM, sms or email but it takes much more concentration to produce error free typing. If email and document editing is your primary motivation for buying a smartphone, you would be much more comfortable with a device with a larger keyboard such as the Treo 755p. After using it exclusively for awhile going back to my 680's keyboard felt like a world of difference.

Phone
The phone uses a digital dual band (850/1900 MHz) CDMA radio. The Centro can access high speed EVDO wireless data networks and can fall back on a 1xRTT connection when out of range of an EVDO signal. Current EVDO speeds generally average around 200-600kbps, bursts of up to 2 mbps are possible when downloading larger files. Of course, actual speeds will vary depending on signal strength and other conditions. You can also use the Centro as a wireless modem for your laptop or desktop computer via Bluetooth or USB cable if you have the appropriate data plan.

Palm has finally made some good improvements to the phone experience. Call volume through the earpiece is now sufficiently loud. Treos have had a notoriously soft earpiece volume in past incarnations, which is why apps like VolumeCare are consistently among the best sellers. The overall volume is now quite loud and seems clearer as well even when maxed out. Phone call quality was also good in my informal tests. I never really experienced much trouble with background noise or other issues hearing other callers. The speakerphone has also been given a respectable boost in volume and clarity as well. The rear speaker seems to be considerable louder and doesn't sound as distorted as past models at higher volume levels.

There has also been a slight improvement in the phone's SAR rate. SAR is a value that corresponds to the maximum relative amount of RF energy absorbed in the head of an active user of a wireless handset. The GSM Treo 650 and CDMA 700p were ranked among the highest radiation emitters in the US with a SAR of 1.51 and 1.48 W/kg respectively. 1.6 W/kg is the permissible limit set for mobile phones in the US by the FCC. The Centro comes in with a 1.35 W/kg absorption rate to the head, which is 0.09 W/kg lower than it's recently released CDMA big brother the Treo 755p.

Camera
The Palm Centro includes a 1.3 megapixel digital camera built into the rear of the device next to the speaker grill. It can take photos at a max resolution of 1280 x 1024 pixels and has 2x digital zoom. It can also record video clips with audio at a 352 x 288 resolution. The camera quality is pretty standard for a phone-cam. Outdoor scenes and good natural lighting conditions will give you the best results, while indoor and low light scenes will often yield unexpected results (if any). Below are a few raw, unedited Centro photo examples taken at the maximum resolution in various lighting conditions (office lighting, sunny landscape, indoors, outside closeup):

Bluetooth
The Centro also has built in Bluetooth v1.2 wireless capabilities. This allows for wireless accessories such as GPS navigation kits and wireless Bluetooth headsets. Native Bluetooth stereo A2DP support is still missing, but there is always Softick Audio Gateway if you'd like to use wireless stereo headphones.

Audio
Like previous Treos, the Palm Centro has a dual speaker design, with the front earpiece speaker used for phone calls only while the rear handles the speakerphone, sysytem sounds, games and music. If you want to listen to digital audio via a headset with standard headphones you'll need to use a 3.5mm stereo adapter accessory. The rear mono speaker can get quite loud and can even function as a small portable stereo in a pinch if you're in a non-noisy environment.

There is a varied selection of ringtones that can also be used as alarm sounds. The Centro has a mix of the classic Treo ringtones as well as a set of new musical ringtones. Most of the new ringtones are quite funky, and I don't mean that as a compliment. The new sounds are an unusual assortment of bad techno and cheesy rock songs. It's a good thing that you can transfer most .wav and midi files via Bluetooth, beaming or hotsync from your PC for use as ringtone sounds. A new freeware utility has been released that will let you create mp3 ringtones on the device from your personal collection. The sound manager application also allows you to record your own custom audio clips that can be used for ringtones and alarms as well.