I just finish picking up all three vaults and the creature guide and I have to say as the GM I really like them. Creature vault is the best out of the three vualts. As a GM put a adventure together is a snap, place out the cards you would need, look over general story line and quick run down of encounters and your set. I dig that with the cards I can see the shape of the story and it has pervented some snags that I wouldnt have caught. these vaults are a stong GM tool. I know didnt invest in the rest of the guides, I do own the other expasions so I felt there was no need to reinvest in something I already own. Player guide is nice but I already have player hand outs, Gm Guide is okay but then I have the rules and errata is online, the best bang for your buck is the creature guide if you own the expansions already.
I thank FFG for keeping up one of the best standards in my hobby.