Same deal with the Secret Wars Omnibus. $100 for the 12-issue series three cross-over issues that don't really matter, and a couple of extras (496 pages). Whereas the paperback was about $35 for just the series (376 pages).
I've heard they recoloured it and the pages are bigger though. And they look nice on the shelf. But still, not worth it, in my mind. I prefer the Ultimate Collection paperbacks that put two or three tpbs together a few years after they originally came out. I have the Frank Miller Daredevil ultimate collection and the JMS Spider-Man ultimate collection (minus the last volume because I swore to never purchase a collection with One More Day in it), the Grant Morrison New X-Men ultimate collection, and the Joss Whedon Astonishing X-Men ultimate collection. They look nice on the shelf too.