Fun, easy
Got all achievements with the Gentleman character (except for the achievements for beating the final boss with the other characters).
You got the "feel" right - the way the guy jumps and moves, the bounding boxes for damage, they are all just right. A lot of platform games get it wrong (like having the character slide too much).
It would be nice if the characters were different somehow (beyond appearance) to give an incentive to replay with a different character.
A little easy - died once in the whole game, in an early level (could have been avoided if I was paying attention). Didn't die to any boss. In fact on the last boss I didn't even get hit once.