Kinda boring, repetetive, etc...
Kinda repetetive, like a said before, as in, the bosses all had a pattern, so it was pretty easy, and also, what about the fact that on the fat bald boss you could stand out of the way of his bullets and not get hit, forcing you to stand behind the wall thing. If you were going to do that, you chouda given him an automatic or something, or made him move his arms, at least.