I really liked the game! I wasn't expecting it to turn into a DOOM game all of the sudden, but I can't complain at all. The graphics and the music all felt very retro and I think you hit the nail the head with this one.
The only real complain I have is that maybe it would have been better if there were checkpoints before or after every 3d room, as after loosing, its a long way to reach the room where you lost.
Besides that, really solid game!