The hand-drawn art-style implies a lot of organic curves; the level you have, half temporary art or not (dear god please tell me it's temporary, right now it's not something I want to be caught playing) is very angular, which again plays into level flow. Something with gradual slopes will appear to flow a lot more smoothly even if the basic routes are the same. Stuff like half pipes not ending exactly vertical, slowly easing into upward/downward incline, everything to reduce the sense of perpendicularity.
Just something else to keep in mind.