I just finished this game on co-op and I gotta say it's some of the most fun I've had in a long time. It took us about 7 hours to beat even with the two of us. You pretty much play as a super-hero luchador in a beat-em-up style game trying to save your princess. There is tons of secrets, in which you don't unlock the 'true ending' unless you find them all. You can also unlock different costumes which gives you different benefits and you can upgrade your skills. I played most of the game with the Diablo suit which kind of made it like hard mode even on easy.
I gotta say this game really did remind me of the old-school games and some of the music even sounded alot like Mario and other games. Enemies were decently hard to beat without being too difficult, but keep in mind I did have another player helping me. Storyline is decent and there is tons of humor in the game also. It's kinda like they took everything people love about indie games and put it into this game.
Co-op design is fairly decent but the camera kinda sucks as it will only follow player one instead of expanding. Every time you die you have a timer to wait to come back and when you do you're a little orb that floats around until your teammate releases you. I felt this made the co-op fair without being too much struggle. Pretty much a fun co-op experience that adds mild difficulty to great teamwork gameplay. Coordinating certain platforming can be incredibly hectic though and we usually just let one person do all the platforming at the hard parts because it was too hard with two people to do.
Co-op is also somewhat buggy... I have a screenshot where instead of dying, me and my buddy just have 3 copies of ourselves each...
I will probably replay the hell out of this game until I unlock all of the achievements. I can't really say too much bad about the game in all honestly so I would have to give the game somewhere around a 4.5/5.