GP2X

[MissaFX]

and I would also assume that setting stuff up on it would be more straight forward on GP2X since you don't have to mess with firmware stuff.

Actually you have to flash the FW on the GP2X too.  And it bricks sometimes with the officially released FWs when you upgrade.  I have no idea how hard they are to fix from this state.

With the PSP if you brick it, you did something really wrong like mess with your ID storage keys or try to run a FW your hardware cannot run (without say Time Machine).  Short of letting the official upgrader check the update.  Then in less than a second swapping the memory stick for one with a corrupted version of the update file on it right before it starts loading the decompressing the files.

[16-bit]

I fully understand why one would choose a PSP over a GP2X.  I also own 2 psps, but I went with the GP2X as well because of my interest in obscure hardware and my disinterest in messing with my PSP. Moreover I prefer the F100mk2 joystick to the PSP1000 control pad.

Anyway, I've had my GP2X for nearly a year and I have gotten great mileage out of it:

Perfect port of Snatcher for the Sega CD
The joystick (I have the F100mk2) is ideal for playing some of my favs: HerzogZwei and International Superstar Soccer.
Near Perfect to Perfect Neo Geo emulation (I mainly play turfmasters).
and now pefect hu card emulation via Temper.

I'll have mine with me at the Midwest Gaming Classic if anyone wants to try it out.

[Kitsunexus]

I still want a GP2X, but I will not sell my PSP for it as originally reported.

[termis]

I like my GP2X mk1 (the later edition, too), but the diagonals at times isn't recognized properly.  It drives me nuts, because it's intermittent, and I hear it one of the more common problems on them.

Older console emulations seem to run good, no big complaints there.

MAME emulation is decent, but still has some way to go, as some of more "recent" retro games (those from say, 90 & up) can run a tad slow, even with overclocking.  But I think there's still a lot of optimization left to be done with the GP2x MAME, so hopefully it'll improve with time.

[guyjin]

If I were going to get one, I'd primarily want to emulate PCE and Game Gear games - how do those fare?

Also, if you can get a big enough SD card, do PCE CDs work?