I liked it...
It was pretty good. You get high marks from me because I'm a huge Doom fan. I think the file size could be considerably smaller, and I attribute it to the assumption that you didn't compress your audio. Some of the action scenes are really cool, a personal favorite being when the Marine pulls out his plasma rifle and wastes a few demons with Crystal Method pumping in the back ground. The final shot of the rocket slowly flying towards the Spider Mastermind was brilliant.
Only thing I'd complain about is the inclusion of the Mancubus. Most would know it didn't appear until the second game.
But other than that I think you did a great job. The music was well chosen and the animation was smooth enough that it didn't draw attention to itself, which is good considering that you were limited in scope of what you could achieve.