Ah yes, the GP2x, I’m happy to say I’m a proud owner of one. It’s a pretty powerful handheld, dual arm processor 200MHz with pretty powerful 2d acceleration and multimedia capabilities to boot.
So far there’s been a huge amount of homebrew support for it ( http://www.gp32x.com -good site), and with the previous GP32 warming things up, the GP2x is set to do a lot better.
It’s also pretty easy to program for since SDL is supported, and you know if it works on your GP2x, it’s likely to work like that on all the others.
It does have its glitches here and there, but generally you have a pretty powerful handheld that’s open and has a great homebrew scene supporting it (with some commercial games comming soon too) with a lot of potential for growth (only released last November) and leaves itself open for you to do whatever you like with it.