A first try in 3dgs and showcasing it, is a hard step to take.
For a first level, this is quite oke, I can understand why you used some standard wads, models, geometry blocks,... because you're of course in a very long but exiting and fun to do learing periode While your project will develop, you'll learn every bit when experimentating so don't start of with shaders or with other complex stuff you want to create or you are willing to create because you'll probably won't have enough experience to complete the though and procres of it The level design of your level is oke but too blocky and monotone, while goofing around with WED,MED and SED, you'll learn and see who it should be done properly ^^ If that level of proces is to slow for you, then you can always follow useful tutorials form the Acknex resource site and lot's more but I guess you'll save yourself it that option

Cheers

Frazzle