What an awesome level! The enemies do get a little spammy, but you know, it's a good challenge. In the fourth room I found that I can't go to the last room, however! I checked it out in the editor, it seems that the teleporter is pointing to the current room instead of the next one. Just a little something I came across :)
For the rest, this level really is awesome. The design is top notch!
Yeah you did a great job building the world but the enemy spawns are somewhat overwhelming.
There is a super fine line between challenging and frustrating, when the player is left with only one possible tactic to win (run in an endless circle and fire into the middle) it becomes more tedious than exciting. You want to lead the player into using strategy without them realizing it.