Nice, I enjoyed that. The death sequence is impressive, deceptively clever and impressively creepy.
EDIT: As for the puzzle which has stumped some people, the readables do tell you exactly why and what you should be doing. Just not where. I didn't have an issue with that apart from lugging the thing from floor to floor to try and find the right spot.
For people wondering about the secrets, since I haven't seen a list yet, I've now found 5 on easy difficulty - my default when playing a new mission. I've not tried the higher levels yet.
These are:
Hope that's useful!