After a weekend with the Centro, here are my initial impressions:
As a phone, it's amazing. Could be all the abuse I heaped upon it, but my Treo did not maintain a signal as well as this phone (though it was still better than most). Most telling was my ability to maintain a call while in my basement last night. That was a surefire call killer for my Treo. Dunno why, but it couldn't hold a signal there. The Centro had no problem.
As a PDA, it's faster than my Treo (duh, it's several years and revisions newer). The screen is brighter and clearer as well. The factory stylus is a joke, light and flimsy. It makes the touch screen feel mushy and vague. If I use the Treo's stylus (metal body), things improve greatly. I'll be replacing the stylus soon. The 4 control buttons are a bit too cramped and I sometimes select the text messenger button when I mean to select the PDA "Home" button, etc. I'll have to retrain my fingers.
The sync software was a bit wonky. It downloaded everything from my Treo, but didn't import it into the Palm Desktop. When I synced the Centro, it downloaded my apps, but not the PIM data. I had to manually import that from the backup folder to the desktop before it would sync. Now that it's in the desktop, it syncs just fine. I never really used the Palm Desktop with my Treo, preferring to maintain backups with BackupMan instead. Speaking of BackupMan, I have to upgrade that since the version I bought for my Treo doesn't work on the Centro (or any Treo since the 680) and there isn't a direct upgrade path to the current version. I have to fork out another $15 if I want to keep using it.
Otherwise, it's great. It has all the features I want in a PDA/Phone without the bulk of the Treo 600. This is my first bluetooth phone, so it'll be interesting to try out the headsets and all. Since DC passed that law forbidding talking on the phone with a handset while driving, I have to have something "handsfree".
Chris