While I liked the whole machines-speaking-to-you thing, I have a few issues:

-The first half of the first depth of the mission is difficult enough, but then it takes a nosedive after. I do mean up to the point where you get to the giant, sprawling area with the pick-up statues etc., etc. I was able to finish the mission with relative effortlessness.
-The right enemy wave room in the second depth needs some revision, perhaps. The Bombheads, being able to die as quickly as they respawn, drop a lot of hearts.
-The boss could stand to be a bit hardier. As for its actual attack pattern, I have no complaint, but I am willing to opt for something more... threatening.