I love unreliable narrators. "David Wong," the hero of This Book Is Full of Spiders and the earlier John Dies at the End (which I've not yet read) is as unreliable as they come. He cops to it at the end, finishing up an incredibly long and subtle joke about the hyper-efficiency of one of the characters, and I punched the air. Considering that I'd honestly - yes, me, honestly - choked back a tear or twelve over the death of a character about four pages previously, I'd call that a win.
This book is a horror novel as designed by Terry Pratchett and Douglas Adams, which mostly plays by the rules it designs, but has some incredibly fun cheats. It's set in a Hellmouth-sorta town, with shrunken soldiers and teleportation tunnels, and only our heroes and a couple of friends know about all the weirdness. So they're uniquely equipped to save the world from an invasion of otherdimensional spiders that manifest, grotesquely, inside your head. They even have access to a substance that freezes time, allowing you to cover great distances while everything else is locked in the moment. But you can't cover the distances too quickly; a moth that is in your path and cannot be budged hurts like the blazes when you run into it at full speed.
Honestly, there might be a thing or twelve too many going on in this book for me to have been completely satisfied with it on a single read. The subplots about shadowy men and secret councils of bad guys never really gelled for me, even as they were important to the climax. But I admire the author's moxie in concocting a really awful scenario and playing it through, writing himself into corner after corner and finding honest ways out of the messes that he's made. It's a story where humanity's survival comes down to two drunk rednecks, a dog, and an out-of-town girlfriend, and somehow - somehow - they conspire to save the day. If you can stomach the awful and gory body count between the first infection and salvation, then I can recommend this, but only for the not-too-squeamish.