A fun Beat 'm Up game I would recommend playing co-op. This is mostly because playing this alone, takes away a lot of the intended experience you can have with the game. Charming artstyle with matching music to tingle your nostalgic brain.

My thoughts:
(+ = (mostly) positive; - = (mostly) negative)
+- Gameplay;
A fine selection of unique characters to use. They all have something that make them feel different. There are sadly not as many levels as I hoped. But the levels that are in the game are fun to play.

+ Music;
Very nice, they clearly put some extra effort into that. The classic sounds are something my ears enjoy.

+ Graphics;
Beautiful game. The pixel artstyle that will never badly age. Lots of expressions and always something new to discover.

+- Story/Characters;
The story is what you expect, nothing special. All characters have their own personality which encourages to try them all to see which moves they can do.

Recommend?
Depends. If you are into TMNT or want an easy game to play with some friend(s) on a couch, then yes for sure. If you're curious, I would wait till there is a sale happening. If you're still unsure, just check a trailer. It'll show what you'll get.