WebOS is the future of Palm. The Centro uses Garnett, an old and decrepit OS that's about 8 years past it's time. And the Centro keyboard is a nightmare. It will be interesting to see what device Palm follows the Pre with, and if they improve the keyboard over the Pre's. Lord, I hope so!
In the mean time, if you want to try an older Palm OS device, look for a Treo 680. That was the most stable of all the Treos I ever owned. If Windows Mobile is more your thing, the Treo 750 might suit you.