Pros: Small Color No batteries required Plenty fast
Cons: Might not serve all of your needs (wireless? more memory? larger screen?)
I was given a Zire 31 on http://www.freecycle.org/ after my Handspring Visor Deluxe just stopped powering up. The Visor was grayscale, so the sharp color screen of the Zire was a really nice surprise. My PDA needs are pretty sparse these days: I keep my contact list, calendar, shopping list (Handy Shop is terrific), and some small games on it. I had stuck with the Visor Deluxe for so long, buying 2nd-hand ones on eBay, because the need for recharging seemed onerous. I'd rather replace batteries.
So when I brought this home, I thought the recharging would be a pain. Well, it hasn't yet! I also haven't experienced the lack of reliability that others have. Since this is second-hand, I suspect I won't (that they'll either die early, or not).
I had scoffed earlier about the button layout of the Zire line. Removing two of the classic buttons from the Palm layout seemed like an extreme move. But I haven't missed them yet! And I ADORE the new Graffiti! What an improvement over the old, where the only reliable way to get a V was to draw it backwards. Really great.
As I said, my needs are simple, and the Zire 31 fits them beautifully, with lovely additions like easier Graffiti and a sharp, color screen.