I got one for a friend, they're nice enough, but battery is an issue (be sure to get a battery pack case like the Mophie Juice pack), app store is OK, but the apps are buggier than those on my hacked iPod Touch.
It has alot of potential, and I prefer it hacked, just like the iPod, main limitations out of the box, no video capture, mediocre camera, no cut/paste, cannot be used as an external drive, files not viewable from Windows, poor speaker, no stereo bluetooth, limited battery life, limited 3G coverage (versus eVDO).
An most importantly for this forum, as a PDA it kinda sucks, the predictive spelling this is TERRIBLE, and a bunch of basic features you'd expect on a first gen Palm aren't there. Get something else, either windows or palm based if it's acting as a PDA primarily.
Biggest advantages: nice screen (still glass), nice media playback features, iTunes store, good web browser.