Good choice. I order all of my omnibuses, Absolutes and HC's from them and thats exactly where i got my GoTG omnibus from them. I've already read all the stories in it already through floppies or trades but it was really nice to have it all collected. There is just so much content in that thing its ridonculous. My only real complaint is the paper stock for Marvel omnibus are super thin and i'm really scared when handling them. I already have a rip in my AoA omnibus dust jacket just from taking it off the shelf. Just handle it with care and read it in a solid place like a table or desk. IST ships super well packed so don't worry about damage during shipping. My only other odd complaint is that they include Thanos Imperative in this while it comes after War of Kings making the reading order a little wonky.
Definitely try to get ahold of the Annihilation and Conquest Omnibuses now and while the whole War of Kings thing wasn't held in very high regards I enjoyed it all so I would suggest picking up that Omnibus when it comes out. I mean, it has freaking Darkhawk for crying out loud!!