Here are 3 demos. I was doing great until the end -for some reason I kept quickloading instead of quicksaving!
Some thoughts: [SPOILERS!]
*I think it's a mistake to have the player need to rocket jump to exit the level. I didn't have enough armor or health to do it without cheating.
*Lighting. You had a minlight setting on your map or you set light in worldspawn (the same thing really). That's really not a good thing to do. As you can see people have noted your map looks flat. It's a shame because there are a lot of moody sections of your map. They would really be enhanced by lighting.
*yeah more monsters across the board would be helpful.
okay on to the GOOD stuff
* I love how you toyed with the player and instructed them with messages. Not too obnoxious. It felt good. Just the right amount.
* drink my blood moment was cool
* hidden wizards (the face in the wall) was a very cool moment
*some interesting uses of textures. some really good and clever - some not so good. Like a wall texture on a lift. :-\
*you had a lot of nice rooms and structures that worked well across the board. The "final" battle room was nice and the surrounding areas too.
*good secrets overall - although I missed some of them
I'd say great work on your first map! It was a large ambitious project and I usually tell beginners to start of small. But you pulled this one off pretty well. You have a great start here. Congrats. I'd still like to do a video on this map if you are interested.