Unfortunately, the biological aspect of this film is way off. That will ruin it for a lot of people.
First, if I saw in the previews that this was another underwater creature film, I would not have watched it.
Creatures living at that depth would not have evolved to keep their eyes and they sure as hell wouldn't have evolved to have limbs (or keep them, since we don't know their origin). That's just silly Hollywood writing stuff.
The acting was fairly decent and the ending featuring "The Unknown" by Bonnie X Clyde was as unexpected as it was... enigmatic? I can't come up with a better word right now.
The film has its good moments and quite a few "fillers" that could have been better used to tell some more of the mysterious backstory.
It's a good watch during these extremely boring moments we're all experiencing, but I only give it 2.5 stars.