Mushroomy Kingdom is a pretty awesome idea, but yeah, it does start to suck when you keep getting into 1-2... 1-1 isn't so bad though.

Mario Bros. just isn't very much fun at all. Same with 83m. I appreciate the old-school attempt but really they don't translate that well into Brawl levels.

The new DK level isn't very fun either. The ice climber's level in Melee was kinda cool but it was very symmetric. The new one is more unpredictable which I think makes it more difficult to play.

I don't really like the electroplankton level either. Really I think the worst levels were the ones that were just taking designs straight out of other games without a whole lot of effort to translate them into suitable Smash Bros. stages.