I actually bought the GP32 for it'e PMP abilities because everything similar to it cost about 3 times MORE. As it stands there's only 2 other devices I know of that could rival it for PMP, One is a virtually unheard of media player with a slightly larger scree thant only plays Mpeg4 from SD card but will not play games and the other is the PSP which is still more expensive and has more expensive Memstick media.
So I think it will do well if enough people know about it... but the Emulation aspect could make it a target if it gets too well known.