I have to admit, this movie is weird. Now I watch a lot of strange stuff, but this one goes in the top 10 strangest movies I've ever seen.
This is a movie that requires patience and time spent actually *reading* the stories it includes in order to understand what's going on. So if you haven't read "The Shunned House," "The Music of Erich Zann," or "Dreams in the Witch House;" do so before watching this. With a quick google search you will probably find the e-texts you need; and I highly recommend going online for this because my own Big Book of Lovecraft did not include "The Shunned House."
I am giving this a 7 out of 10. The movie moves fairly slow, and some scenes the acting was not stellar. However, the old world imagery and style is consistent; and the music is good. There were complex female characters, who despite being written vaguely at least acted well enough to add to the ambiance of their scenes.
There's only a few critical things I would say about this movie:
1. This movie will be too bizarre for people who are not already Lovecraft fans. They will not be able to understand the context to each of the story lines.
2. The plot moves incredibly slow, and is hard to follow. It tends to jump from the main plot line to the dream sequences in no particular order and no particular reason than just to do so.
3. The movie did not include anything from the ending of the book "The Shunned House." It would have been nice to see the protagonist return with vats of acid to cleanse the hideous cellar of it's monstrous mold- ridden fungus-creeping alien influence like he did in the book. Then again, I can't think of any Lovecraft movie that had a happy ending. So at least it's consistent with the genre so far.
In conclusion, I don't think it's terribly awful. It seems like the producers of this movie put a lot of effort into this; only to have their creative vision unappreciated by those that can't be bothered to read the books in the first place. So, just take the time to read the books first. This is not a movie that can "teach" you Mythos.