Ive heard of a lot of reasons of why people sold their Wiis, but never have i been confronted with 'RE4 Wii sucked so i sold me Wii to me sister'. Im sure many Wii owners (including myself) would consider RE4Wii as currently best Wii game.
I played RE4 on GC first, never played it on PS2, then bought it again on Wii. The Wii vesion feels supiror, even when plugging in the GC controller. The one thing i hated was flailing like an idiot in those chase/boulder sequences.
Haveing yet to play the RE5 demo i cant really comment on the game.