I agree with a few of the minor gripes in the other comments (mostly overly stick wall jumps) and the boss fight seemed to be bugged for me so unfortunately I couldn't see the ending (I could beat the first guy by stagger locking him but the the second one just went invincible and changing modes did nothing besides stop/starting the platform).
Overall though this was fantastic, I loved the little touches like having a different aspect ratio on the 8-bit version, really increases the overall charm