I know that I'm 5 years too late, but I finally completed the game. The tower climbing levels were by far my favorite! Plus the physics and having to deal with teeter tauters and Ferris wheels while being chased by skeletons and seeing them react to the environments was enjoyable too.
I also like the fact that with the collectables, I don't have to get them again and again when I enter a level, I can just speed run through and grab the ones that I don't have. Good design choice.