I found TERRORTOME to be a hilarious, uneven read. I think anybody with a love of language and writing will find something to love about his hilariously bad prose. It's also one of the most meta books I've ever read -- Garth Marenghi is already the affected "author" of this book, but here he is writing about a protagonist (Nick Steen) who seems to be little more than a fantasized ideal of the Garth Marenghi character. When his brain is "squeezed" and all his creations pour out into Stalkford, he and his editor are forced to deal with both survival as well as how nonsensical or overwrought his constructs can be.
Some highlights for me were:
The wonderful, meaningless map at the beginning which hinted of epic locations that were never visited
Almost all of BRIDE OF BONE
The low speed car chase in DARK FRACTIONS, described with gripping high-octane phrasing
His endless litany of "Rasher" fiction novels
The trip to Stalkford's petting zoo
I could have done without the more graphic kink involving his typewriter and the torture/disfigurement in the first book. It was admittedly described in rather abstract terms, but I enjoyed his goofier spookiness that merely threatened violence.