@kenny: I disagree. I suspect most people don't like the Go simply because... they can't afford one. Same reason why PS3 was hated and is now loved... because it's affordable. That or they already have a PSP and want to be able to use their UMDs on the new model.
Personnally, I don't care about old UMDs I didn't have any PSP before my Go. Sony clearly stated non PSP owner was the target here...
I don't care about reselling games, I never resell games and so do many people like me who can pay 250 € for a handheld console. I have better things to do with my time than selling games, plus I enjoy collecting them anyway.
I don't think it's awkward to hold and play at all, I actually prefer that handling to the classical PSP handling. Feels more like a DS or old 'games and watch' first video games. Controls are better at the bottom, not on sides.
So what I said still hold true for me. Lighter, sexier, more portable, with a better screen. Keep your 3 kg old PSP and don't forget to bring the 12 UMDs with you. All I see is it wouldn't even fit in my pocket...
To each his own I guess...