I thought it was okay. I do not understand Von Trier's recent aesthetic shift -- I am not a huge fan of Dogme 5, but one thing you could say about it was that it was not referential. It developed it's own logic and boundaries. In this film, the cinematic quotes are an overwhelming noise. The Pasolini style tableau in the opening sequence, the direct visual evocations of Last Year at Marienbad, the... well, everything was Tarkovsky: http://www.youtube.com/watch?v=eXj9dOF_vb4
Familiar?
And then there's the plot, which is vaguely reminiscent of Tarkovsky's last film, The Sacrifice, in which a family awaits a nuclear holocaust in a remote cottage. He even lifts some direct imagery:
http://www.youtube.com/watch?v=kObc2F7otrQ…
And many other similar quotations to The Mirror.

Then there was the unintentional (?) camp elements. I love John Hurt, but why cast Caligula as the father of the bride? The voice-over on the letter left on the bed is a gimmick too far -- perhaps trying to be playful with Hollywood convention, but wildly off the mark tonally in this film. I found myself laughing when I think Von Trier was probably straight-faced. The Nietzsche Wept scene (the beating of the CG horse) was a bridge too far -- an art house joke.

The acting was all around superb. Charlotte Gainsbourg is a showstopper, but the biggest surprise was that both Kirsten Dunst and Keifer Sutherland show real acting chops. Who knew?

Kind of a big, digitally colored mess and the work of a director trying too hard to canonize himself into the pantheon of great European directors. It's a little embarrassing, but not horrible.