Just played this. I'd agree with all that's been said about the weapons, especially the gun smoke (you might want to try reducing the alpha). Also, I'd suggest toning down the amount of sparks generated by shotgun puffs. Also remember that we have multiple death states for BulletPuff, so I'd certainly recommend getting rid of the sparks for hitting a bleeding actor.
The maps themselves show quite a bit of promise, but are still going to need some severe spit and polish. I'm not talking Tormentor detail here, just a bit of incidental detail - at the moment, with the exception of the weapons, there isn't a great deal going on to distinguish this as a ZDoom mod at all. And MAP01 needs some major attention, particularly in the latter half - it's practically indistinguishable from the original.
The ambient music kicks ass. Hell, if no-one's called it yet, can you put me down for MAP04? It's a smallish level, and since this will be the first map I've ever released (note: by no means the first map I've made), at least if it sucks it won't be too hard to fix
EDIT: Damnit, MAP04's taken. Still, I'd like to volunteer for any other maps that are free.