Jeph Loeb used to be able to write good stories. Long Halloween, Dark Victory, Hush. These are names that inspire feelings of excitement in many comic book fans, but Loebs run on the Ultimate universe seems to be met only with disgust. And with good reason.
The idea of Magneto creating a wave to wipe out humanity is a decent start, it's a good worldwide catastrophe that throws the world into peril, and many heroes are lost. But here's where things get iffy. While heroes should be sacrificed for the sake of such an event, there was no need for such graphic gore and many unecessary deaths just ofr hte sake of it. One character is crushed to death and we get to see his head explode over 3 panels. That's not shock violence; That's self-indulgent grotesquery. Another character has their dead body cannibalised and we see their entrails ripped from their stomach. The Ultimate universe has always been dark and violent, but even with the violence of "The Ultimates" 1 and 2, Bryan Hitch and Mark Millar had the sense to use discretion shots, which kept in the shock of the violence, without being needlessly vulgar.
Besides the quibbles with the gore, which many may call me squeamish for, which I assure you I am nothing of the sort, there is also the ridiculous conclusion where the climax is done in the space of five seconds, and feels totally out of character and completely forced, wasting years of build up.
The art itself is competent but the writing is lame. Spidey and the Fantastic Four have more or less no involvement in the main event of U-day and it's all X-men and Ultimates. The side quests that the four and our friendly neighbourhood webslinger are led on seem only to try and add in more deaths.
Overall a thoroughly bad piece of comic book writing, whose only solus is that it paves the way for "Ultimate Armour Wars" and Mark Millar's "Ultimate Avengers" which are fantastic reads.