Well, firstly the obvious: this is a HUGE book, with 700+ pages and very well presented.
This covers not only the monumental Fatal Attractions storyline, but also some of the build up to it. The main event, though, is what everyone will be interested in, and it has some cracking moments - Ilyanna Rasputin's death issue is incredibly poignant, and the final face-off with Magneto is classic stuff. I had heard that some of the Lobdell-era X Men titles weren't up to much, but this was pretty good stuff.
When the upcoming Bishop's Crossing HC comes out, there will be an unbroken run of UXM from Inferno through to the end of this book. That's an awesome run..