Is that last level even clearable? I mean, with only one floater, I don't think I can get up to the others to save them... and there a one-way wall blocking them! Unless there's another entrance I missed in my play-through...
Overall, good level designs. I liked the second level's trick (Although I would have given the player more space to pull it off...), but I think I back-routed the first level, thanks to the fact that a lemming dropping directly over the exit will enter the exit regardless of the fall involved.