Yes it could have more variety of enemies, yes it could have different room layouts... but for me that doesn't really matter... it was great fun and did exactly what I wanted from that type of game.
Glad to hear, More rooms, enemy types and weapon types were definitely planned but had to cut it all to complete something. I have a lot more ideas for all of those though so I will most likely continue on or start the game over with a better foundation and make it more awesome :P