I have never seen a movie that was this sublime and powerful. It is a fascinating interwoven psychological drama about the end of the world.
I would say "Great." It was mesmerizing. I left the film feeling lonely sad and also terrified. It was like an exceptionally vivid nightmare brought to life. That someone had the guts and the artistic ability to put it on screen was inspiring. My hats off to Lars von Trier.
Probably won't get wide play as I doubt that many will "get it". I went with my ex and she feel asleep and was totally bored. It was like taking a deaf person to see Beethoven's 9th. She totally missed the feeling part of it.
I realized that your view of this movie will probably be related to your view of another weird and "deep" movie from earlier in the year "Tree of Life". If you liked one you will likely like the other. Many will hate both and wonder why anyone would pay their respective directors to make them. Others (like me) will praise the directors. Particularly this one as one of the greatest ever to put artistic talent to film.
Too bad it won't get wider play - but I'm guessing the economics of a "deep" movie like this are pretty sour to say the least. Anyway - if you like weird deep movies that explore human emotions and our connection to the universe in a complex way you will enjoy Melancholia.