I hate it when dead characters come back. If they only do it once, for a very special cause (Like in BSG), it's okay. But if they make it easy for dead characters to magically come back it makes it so character death isn't a real threat, and the jeopardy is reduced in future storylines.
But they totally should have killed Kim instead of getting rid of Kes. Stupid sexiest man list, who the hell would ever find Garrett Wang sexy beyond the standard amount of sexiness necessary to be on TV?
I dunno, no one minded when they brought Spock back from the dead.