Using the rocket booster in the pipe causes the cycle to become disjointed if the pipe gets too long. Also I'm still getting my points robbed when I cartoonishly faceplant after beating a level.
Otherwise the pipes and push zones play great. By their nature they're much more forgiving than any of the other mechanics which leads to the spaceship being significantly easier than all of the other stages. Not necessarily a bad thing, it just stands out from the others as forgiving.