So, just finished it. Pretty short, but I had a lot of fun. The level design is probably my favorite out of the lot so far, probably because the environments were really well done and there was generally quite a bit more going on in a given area than in the first two. Granted, most of that was meaningless background stuff that was only there for visual appeal, but coming from someone that felt C2 was a little on the bland side it was still a welcome change.
The typo in the fight against the sudden plot device was pretty great too.
Not really sure how I feel about the story yet. The various data pick-ups that detail things about the Ceph were certainly cool, and I liked how threatening they were. I also really liked the majority of Prophet's dialogue, especially near the end. However, as has been stated, there's one glaring flaw with the way the Ceph are presented this time around that kinda annoys me. The fact that it basically jumps out of nowhere is even worse.