Played both parts yesterday.
It's a cool map with some nice tricks. Visually solid, a few things stand out as very good, although overall this is less of a setpiece map or one with many distinct or clearly memorable areas. Not meant as criticism.
I like the flickering light in the cracked ceiling right at the beginning. It enhances the geometry nicely. The flesh/infestion bits could have been used more aggressively. Not random bits or backdrops behind lose floor/wall tiles, but made to look like it's actually growing over the facility, bending the surrounding tiles and panels inward etc.
The interconnected layout allows for some exploration and a couple of extra rounds in my case. Bit derping there, but I didn't feel hopelessly lost. Maybe next time when doing an open button hunt level, try to make each route stand out somehow to aid navigation. Not handholding or overly obvious things, just something to let the player realize he leaves the area he's supposed to search. The three buttons are fine really, the signs help; I think my 'problem', if you can call it that, was finding a way to disable the security protocol. And I initally missed the slot for the chip. Partly my fault, though it would have helped if the machines were more pronounced, prominently placed in areas of their own without the risk of some other details distracting from their important role (in this case the cargo train and the laser/transformation device).
Details were good, though the rooms and corridors' basic shape is often quite boxy. This could be something to improve upon.
Gameplay seems fine overall. Would have wished for a more grenade launcher in the open sooner. I failed terribly at secret hunting... and in consequence missed like 40 enemies. Optional areas are a nice thing for added replayablility - though I think I would have prefered knowing about it. Being able to see (look into) additional areas that are intitially inaccessible. Since the exit is unmarked in this map (generator pit), one usually only realizes having missed a chunk when it's too late.
Two showstoppers: I ran out of ammo in the transformation chamber (second chip slot) and inadvertedly died trying to axe the spawns. I suppose normally this wouldn't happen, or maybe more testing would prevent it, but I'd suggest in such a situation it's better to not solely rely on a counter to open the door again, but also a timer - as safety net of sorts.
The second one is at the beginning of the second map. The armor triggers the ambush which then opens the way to progress. However, I still had some yellow armor from the previous level and no way of damaging myself enough to be able to pick up the blue armor for the ambush which means I was stuck. For such setups it's always better to have an actual trigger activate the ambush instead of the item itself. This is somewhat related to a problem that arises if having weapons target something vital on coop mode (which doesn't work due to a bug in the code).
The exit area in the second map was a bit of a problem for me, because I was low on health and the terrain made for some awkward movement.
You can watch me play it on stream
for the next 7 days. Just skip forward until your maps start.