Commendable effort, but you're falling into the same pitfall as mainstream indie game developers.
Instead of adding the 3D gimmick, you should have concentrated on polishing the existing 2D engine, and adding a considerable amount of new content, gameplay features, etc.
3D makes it both harder to develop, and more frustrating to play in cases in which you cannot see level hazards because of the camera angle. It is generally proven that 3D sidescrolling platformers are a bad idea.
On the slight chance that you developed a smart way of converting the 2D layout to a 3D one without much effort, congratulations.... but you should have concentrated on something else.