At the risk of sounding like a broken record, THIS volume is the strongest of the series. 
 In comparison with all the rest, writing gets progressively stronger, the plots less disjointed, the characters more sharp and the overarching story more defined. 
 And no, there's no real need to read them in the suggested order. In fact, I doubt anyone would really complain, knowing all the facts, if some random bloke like me said, "Skip the rest, just read the last one. You'll be kosher." Because you will be fine. All the story elements are there, and while the initial reach and problem entwining all these novels together is resolved in this one, we're not missing a thing from the other novels. Yay! 
 It really is the most solid of them all. Unfortunately, you can also tell. And then the series ends. 
 I can honestly say I love what happens in the novel, and while I'm not too huge on paramilitary operations, the action sequences were pretty damn good, the descriptions and rulesets to the magic and the beasties were much more well-defined than the previous novels, and Fix has finally been fixed. (The opening sequence notwithstanding.) :) But that was on purpose, so I'm not holding his drunk-ass accountable. 
 The most positive and interesting thing I can say about the series and Fix in particular is that he never gets too big for his britches. No unexplained power increases, no deux ex machinas. It revolves around solid mysteries that happen to have a lot of connections to the supernatural beasties now overwhelming the Earth for some reason. The normal bloke makes good, and the last novel doubly so, but I say this from a style viewpoint. 
 Of course, now that the series is ended, (as of this writing,) I'm sad to see it go and a bit angry that I won't get the chance to revisit it now that it HAS gotten good. If I were mean, I'd probably knock off a star for that, but I feel generous. I want to let the novel stand on its own.