Main points of GP2x over GP32?
- Picodrive is even more awesome than GP32 megadrive emulation was, and includes Sega CD and SVP support.
- Amiga emulation is playable (but not full speed, I believe)
- CPS2 emulation is full speed, or close to, though MAME isn't really the thing to use for it - Final Burn Alpha is *much* better.
- Neogeo, Neogeo CD both work very well indeed, but you'll probably have to go through the respective readmes.
- Snes is not generationally better than on the GP32, but is nonetheless better; if it's SNES you're after, wait for Pandora.
- GBA is not full speed in terms of no frameskip needed, but it is in the sense that most GP32 emulators are - i.e. Frameskip 2-3 (sometimes even 1 is enough) gives you an experience that feels full speed, just not quite as smooth as it might be. This is THE way to play Yoshi's Island on the GP2x, among many other things.
- Games by Alex and Ruckage, among others, aren't out on the GP32, and are beyond mere awesomeness. Cave story, Noiz2sa, and many others present, and provide hours of high-end homebrew entertainment. MH-T managed to pull off the impossible, too, and as a result, there is a native version of Albion.
- Duke Nukem definitely works on the GP2x. Not certain whether there's save, but I believe so. You may also be interested in Heretic (and maybe even Hexen? I forget), which work, and in Descent.
- Video is a MUCH nicer experience; no need to re-encode, as long as there's space on your SD.
There's inevitably quite a lot more points as well. The crucial question is whether it's worth getting a GP2x now or waiting for Pandora. That will come down to whether you want to spend ~£100 on a mature platform that does gaming and video really well now, or wait a couple of months, and spend £200 on a startup that will probably in short order beat the living daylight out of the nevertheless awesome GP2x. Your call, there.
EDIT: Thanks Sbock! My mistake!