My brother and I are planning on seeing this tomorrow, and the reviews so far seem pretty favorable.
Elisa is a mute, isolated woman who works as a cleaning lady in a hidden, high-security government laboratory in 1962 Baltimore. Her life changes forever when she discovers the lab's classified secret -- a mysterious, scaled creature from South America that lives in a water tank. As Elisa develops a unique bond with her new friend, she soon learns that its fate and very survival lies in the hands of a hostile government agent and a marine biologist.
It's a strange movie in many ways, but those ways are good. The cast is very good and it's a very nice production. It's rated R for some sexuality and nudity, but it's generally fairly light hearted. Del Toro provided all of the creature's vocalizations, and in interviews said that the design process for the costume took 3 years. It looks very impressive onscreen, so I'd say time well spent.