I've got an IPAQ H6365, I love the convenience of having a pda/phone/MP3 player/video player. If I were to get another one I'd definitely go for a faster processor and a better camera (with video capture). I think GPS would be a big bonus too.
The specs of the i-mate JAM look pretty good, except it doesn't have WiFi. I don't know how important this is to you but I like to go into starbucks and chat or check my emails. For this reason alone I wouldn't get it.
If I were to get another unit, I'd look closely at:
- Processor(I currently have 167Mhz, all the competitors have 400+Mhz)
- Bluetooth - Must have
- WiFi - Must have
- GPS - not critical, but it would be extremely useful.
- IR - I only use this for my remote control, so I COULD live without it. But it's still really useful. And awesome.
- Camera - 1.3 megapixel minimum. Must be able to capture in reasonably low light, and also be used as a video recorder too.
Mobiletechreview has a really useful review.