Solid mechanically, lacking in design. At least, up to level 5, as that's where I gave up. Level design is bland (not helped by having each palette take up seven levels), and the cramped design means that your only real evasive maneuver is jumping
Suggestions:
*More stage gimmicks (spring pads, teleports, temporary platforms, lock and key puzzles, hazards, etc.)
*Shorter levels
*More level variety
*More palettes