Wow, great feedback guys! One thing to note, I'm just designing the rooms, the bosses that go in them are random, so I try to make some rooms that are good for some bosses, and some that are good for others, knowing that some fights will be easier or harder because of it. Once a few more bosses get added, it will really up the variety. Itchykobu, I see what you mean about that platform, I'll probably add some crates to it, so that you will only be able to walk the entire thing for a short amount of time.
FallingStar, for the first one, that's exactly what I had in mind for the tunnels, of course, if I could decide that kind of thing, I would also have put a monster spawner down there, but, you can't do it all. :-)
Anyway, thanks for the feedback. I'm taking a break from making more rooms as I type this. :-)