yeah sunshine get's quite a bit of criticism, I enjoyed it. one of the main reasons for it's unfair criticism is due to it being so different, nintendo stuck a FLUDD on Mario's back. that idea most likely came from luigis mansion (poltergust 3000) as both games were in development at around the same time and both were released in the same year. (PAL 2002)
but what most people do is compare it with what came before and after it, meaning Mario 64 & Galaxy. when you compare it to them imo, it's not as good. sunshine received stellar reviews! but it's never said on it's own, it's always being compared to its predecessors/successors, im not saying it shouldn't be, but that's probably the main reason for some of the negative comments.