The core platforming is actually pretty fun but this game is ruined by the absolutely atrocious boss fights.

It's not so much that they're difficult but that they're long and tedious with no checkpoints. It's no fun getting cheap-shotted and having to play the whole fight again while sitting through the unskippable animations between phases. It's excruciating, enough that I dropped the game about half-way through the campaign. Life's too short to get this pissed off about poor game design.