I know it's not co-op but I read reviews and user comments on various sites and eventually decided to give the game Shadows of the Damned a try.
Now, I will admit I was VERY unsure if I wanted to bother as Suda 51 is not the best name to trust in videogames in my opinion...personally No More Heroes was a few okay ideas with an interesting look and play style that got destroyed but too many bad design choices and unwanted play mechanics.
That said, Shadows of the Damned is worth a try. It has the sens of humour of a 12 year old boy...okay, at 34 so do I ...but it is fun in it's own right.
The story is ridiculous and it's made to be just that way. Very much made in a grindhouse style of movies gone by, this game pays tribute to many horror movies...I guess that could be bad if you don't like horror movies. Also, the mechanics of the game are more solid than I thought they would be.
Here in Canada right now  EBGames (Gamestop) has a deal on that if you buy a game from the list, Shadows is one of them, you have 7 days to play it and then get full value for the game towards another on the list...so really I lost no money and played this baby! In a few days I have played through Transformers: Dark of the Moon, Gren Lantern: Rise of the Manhunters, and now Shadows of the Damned...all for one payment of $59.99! And I still have more titles to try before the deal ends!
Anyway, give Shadows a try and see what you think. If you like it, it has over 10 hours of gameplay and a fun style to it...you won't be sorry. Just be prepared for a lot of $#!&$ jokes, even more gore, and a rather funny sidekick that speaks to you rather often througout the game and is both a siedkick and any weapon you need in the game. I'd put more, but it's not worth spoiling everything for you...go get it!
Great game!