Super fun game. Been playing it in EA for months and love it. The dev (I think it's only one dude making the game, could be wrong though)is very involved with the community, taking suggestions and changing things/adding things. Graphics are top notch to, for a small indie game like this.
The attacks do get more varied and the mobs get bigger as you progress of course, but at the moment there are only the 5 floors to go through before you beat the game. But then you have all the different characters to unlock for future play throughs/doing things in the game etc.
I highly recommend it if you are a shooter fan or a fan of the "rogue-like" genre.