I agree with many points you brought up, but not the underwater battles...
As much as I loved ALL XCOM games (Apocalypse and the two new XCOM games are my favorites) - I hated "Terror from the deep". I hated the graphics most of all. How could they make it so ugly after making the beautiful UFO game? And it was all so pointless!
Anyway, I don't want to see underwater levels or bases or anything. NO WATER PLEASE!
Just sayin...