I love losing to bosses. That normally means I'll have to use my head and do something different. Losing against normal enemies are a pain in the butt (unless it is a strategy game) as then it's just the fact that I'm bad, and that's a bit harder to change.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS