I'm a Handspring Visor (Edge) user. Before that I used an IBM WorkPad C3 (a Palm V OEM), a Palm IIIe, and a Palm Pilot. I have seen/played with Ipaqs and I own a developer edition of the Agenda VR3 (which I actually think is an okay device).
Sorry, but in my experience these pocket PC equivalents are simply not made to handle PDA type stuff. The system is too big, too bulky, too feature rich. To me, a PDA is an assistant, not a replacement for a PC. They're designed (at least in PalmOS' case) to handle tracking appointments, addresses, to-do lists, expenses, small stuff that you need hour to hour. They give you just enough power and data to allow you to be equipped with information while you're not sitting in front of your main computer.
The idea of having stereo sound, full motion video, etc. on a PDA seems ludicrous to me. I mean, when I'm walking from the kitchen in my office building to my actual office, I'm never struck by an urge to watch 30 seconds of The Matrix, or crank up an MP3 file (my RIO 800 serves that purpose much better than any PDA could), or play some Quake. All that stuff on a tiny little screen would just annoy me. Keeping tabs on appointments and having a device beep at me 5 minutes before I need to be somewhere, though, is truly useful.
So, to pocket PCs I say "no thanks". I'll keep my PalmOS based Visor. The rest of the uberGeek world can give itself tunnel vision playing xbill on a 3x3 screen. I'm sure I'm in the minority here, but I simply can't understand how people can consider handhelds as being PC replacements. It just doesn't add up...