Quite decent for a "First"; there are some nice ideas in this.
As a first, of course there are some 'standard' issues; blocky, lack of detail/decoration and so-so lighting. But this is stuff that will improve with routine.
Mostly quite decent monster placement , except for two details:
-In one spot, the monsters 'beam in' in clear view of the player
-In several spots you can stand safely, and the monsters can't hit you, so You can just pick them off at will.
As stated, this can be learned. That's just the mechanics of mapping. The really important stuff, the ideas, is absolutely there already!
I expect the next map to be improved, and i'm quite eager to see it!
Welcome aboard, thanks for your work and for sharing!