I got my Onyx Centro through WireFly, for free, with a new sprint service plan, and I'm plenty happy with it. Lots of great first and second-party apps, a few confusing third-party apps, and a slew of development support, by both the community and Palm, make s me feel good about my decision.
Garnet (Palm 0S 5) is a fairly versatile system, and the customizability (once you get the proper apps) makes it worth the time to create whatever I want. It supports Java programming and the featured Blazer internet browser isn't anything to sneeze at. I can also get other browsers (Opera Mini, and others) but only Blazer, for now, supports integrated downloading.
This device is designed to be your connection to the workplace, with apps for productivity, entertainment, and connectivity. The phone is not the only feature, and when someone at works accuses me of texting, I show them the app I'm in and say, "This is not a text message." That's just snarky, though.
It took a short while to acclimate my thumbs to the qwerty keypad, as well as learning that the tip of my fingernail was way faster than the hide-away stylus... though, sometimes the hi-res event areas are too small for anything but the stylus. High-resolution, by the way, on this thing is beautiful. Go ahead and snap a picture, or better yet, load a large image onto your micro-sd and take a gander at it with the image viewer; panning, zoom, alterations, it all looks great.

I purchased one of these last month, and have been nothing but impressed. The cost (which was part of a 2 year extension on my cingular contract) was about $100 and this unit does everything and does it well. The keys are a bit small for my taste, but still very usuable. The audio quality (when used on a car stereo) is fantastic. I had been considering purchasing an ipod, but this does the job good enough (when using pocket tunes). If you need a nice, but inexpensive PDA, this is a great choice.