So, yeah. It left me...bewildered. Not that it wasn't amazing, but that ending...yeesh.
For those of you uninitiated to the awesomeness that is this story, it was written by a certain Howie Lovecraft back in the day, and is arguably one of his best stories. The basic plot (which the movie follows) is that during the floods of Vermont in 1927, more than just dead people were washed down the river. There were other dead things, and they didn't look particularly human. After a flurry of letters to the editor about the phenomenon and a rousing debate with a forerunner of Giorgio Tsoukalos (sans Centauri hairstyle), folklorist Albert Wilmarth starts receiving letters from a Vermont farmer named Henry Akeley, claiming that these alien creatures hang out around his farm and eat his cheesecake when he's not looking. (Okay, not that last part.) In the movie they have his son George come deliver the message, and a strange phonograph recording of a ritual involving the creatures. Has something to do with worshipping Shub-Niggurath and Nyarlathotep, and even Wilmarth is genre savvy enough to know this is Not A Good Thing. Unfortunately the poor bloke becomes increasingly genre blind as the story continues.
The movie expanded a bit upon the story, naturally, but they did it in a way that wasn't at odds with the atmosphere of the story. It is filmed in black and white and very much has the feel of an older movie, down to running the credits before the movie begins. Unfortunately they did not have a "Cthulhu and Friends" cartoon before the movie. The acting was wonderful and the effects done very well for the budget. This was produced by the H.P. Lovecraft Literary Society, who make it a point of making Lovecraft movies that are not lame. They definitely succeeded with this one.
On one last, parting note...
When I was your age, Yuggoth was still a planet.