Seriously, skyscraper is only hard because of the second level bandage, and the last jump of the third.
I agree. In general, I had some troubles here and there (especially during Cotton Alley runs), but Skyscraper and the Kid's warp were easily the ultimate challenges for me.
The first couple of times I played the second stage of Skyscraper I didn't realize you can slide down to the beginning after getting the key. I died a few times trying to use the main route to get back to the bottom. Finally after accidentally dropping from the ledge and finding the shortcut I felt too owned to describe it in words.