I've been a Palm user for a long time -- since the very second version of the device. I got pretty good at Graffiti, which I tended to use more than the onscreen keyboard. My third Palm was a T|X, which at first I liked quite a lot. Very clear, colorful, and large. I do a lot of writing on mine, or did.
But I wound up being pretty unhappy with it. The digitizer got out of whack, and short of replacement there seemed no fix for it. The screen also got scratched up quite a bit, although I took reasonably good care of it.
Over time, I also got irritated by having to carry both it and a cell phone.
Enter the Palm Centro. The library has a Verizon plan which allows for regular upgrades of phones. The Centro was just $49. I was able to get it to sync with PCLinuxOS and Ubuntu very easily (and with my assistant's Windows PC). All of my contacts, memos, calendar, etc. came over lickety-split. I particularly appreciate that it used the same USB synch cable as my T|X.
I like it as a phone. It continues to work well as a Palm. The smaller size isn't really a limitation, and the built-in keyboard is much faster and less error prone than graffiti was.
I'm finding that I do more texting lately, which isn't part of the library plan, so I have to pay for that piece of it. Nor are we paying, at present, for email/data, although I really don't see the Palm as the best tool for that.
On the whole though, the Centro seems to do just what it's supposed to do: provide a low cost entry into the functionality of the smart phone. It's easy to use, handy, reliable, and integrates well with my other devices. I haven't tried the bluetooth keyboard with it yet (which I got for my Nokia internet tablet long ago), but don't anticipate any problems with it. I also like that it's quite easy to access all my data even when I'm on the phone -- just put the call on hold, toggle to speaker phone, or do both phone and Palm stuff at the same time.