Ultimatum takes a universe so wonderfully written and does unspeakable things to it.
I'm not going to spoil it, but if you don't even want to know minor details, don't read this: (Basically half of the characters die. In a bunch of horrid ways. In at least one instance, cannibalism. Most of the participants are horribly out-of-character, and the basic plot is that Magneto is trying to distroy humanity. Again.)
.... okay then.
Well Loeb's hand is definitely in this.
I might read it just to see how crappy it is.