it's all about the games.
yeah the gamecube didnt sell that well.
but with metroid prime 1 and 2, windwaker, eternal darkness it had some games i enjoyed more than most of the games i played on the ps2. (i own all the 3 consoles of last and current gen, so i'm only looking at the games).
metroid prime 1 is worth buying a gamecube (or a wii with the collection)