The game itself is okay. There is a relatively weak SP, and couch-co-op only, so that hurts my opinion of it significantly. The majority of the game's content is only accessible if you have another friend who can come to your house and wants to play this game. There is an expansion coming out, and surprisingly, considering how little content there is overall, the expansion is not free. The dev is of course free to charge for DLC, but it just seems to be a bad move to me. Personally, I'd make sure the base game is stable and substantial for the current audiences it caters to (SP and local split-screen) before I'd ask people to pay for me.
One of the dev's forum admins is a little trigger happy on the thread deleting as well. They seem to get rid of anyone with anything negative to say.
More recently, there's this http://www.polygon.com/2015/2/10/8011477/towerfall-anita-sarkeesian
I've seen multiple threads of people calmly discussing this, without negativity, just curiosity, and those threads get deleted as well.
I did play over 4 hours of the game as well, so I'm not one of those people who plays for 10 minutes and gives a bad review.
EDIT: They delete threads that even mention the deleting of threads. Seems like the only place you can speak your mind is in the game reviews.