Buying a comic prequel to a film that hasn't been released yet is a gamble. For starters you have to operate under the assumption that the film the comic is setting up is going to be any good or that you we actually going to like it. Second the comic has to measure up to the film once it does come out, although the expectation most times is the comic will be passable fan service at best. Finally, it all has to be worth the time or money, altogether. The money you put into buying the comic plus the price of the movie ticket has to total a certain amount of enjoyment to make it worthwhile.
Pacific Rim better be one hell of a movie. I'm banking that it is as I've been terribly excited by the trailers and the concept is a natural for me to squee over. But with this book I'm already into the property for $25 and I don't feel I got my money's worth so the film better make up the difference.
Tabs from Year Zero its a good read but it's not extra special hardcover material. Its good background matter, good set-up stuff for the world and some of its characters (l swear though if this film has a running narrative that is basically a news story or article, as this book sets up that it might, I'll be very peeved) but it's not monumental. It's deleted scenes, and not the ones that you wonder why they weren't in the film.
Mainly though, the art doesn't live up to the format or price. Were this a $10 collection or 3 $4 comics I would be less harsh but an original graphic novel at $25 needs to look amazing, which this doesn't. Serviceable, yes... but it needs a detail artist, one that knows how to really nail the collateral damage of a mech vs kaiju fight. Art Adams, Gene Ha, Phil Jimenez... these kind of guys. It's a pretty bland looking book as is, though decent reading.
Compare this to James Stokoe's Godzilla: The Half Century War and the difference is palpable... and disappointing. Come on del Toro, make a believer out of me.