I've had the original edition of Nightmare Movies since I stumbled across it in a used bookstore in the early '90s. I have read that thing to pieces -- Newman wrote a classic of film criticism, which makes a great guidebook and a great leisure read alike.
The updated edition takes us up to, pretty much, right this second -- he covers everything right up to movies that were released in 2010 and 2011. To do it, he took the original book and the left the text intact but added footnotes when he had changed an opinion or had something new to say. To this is added essentially a second entire book covering everything released since the first Nightmare Movies went to print. This makes the new Nightmare Movies a big ol' volume indeed, and formatted very differently from the original -- notably the full-page photos are gone, and the movie stills are much smaller and fewer, crammed into two inserts. The proofreading, sadly, sucks -- it's full of inconsistently spelled names, typos, and howlers like "serial" for "cereal." I don't blame Newman for this -- I blame Bloomsbury. For shame!
There's lots of good and interesting stuff here, including Newman's reflections on the "torture porn" genre, the vampire romance phenomenon, and J-horror. The new content is, however, a little less sparkling than the old. Part of it is that he's not starting from scratch to consider, say, vampire films, because he already did that in the original, so some sections feel more like a laundry list of movies than a fresh appraisal -- and part of it might be that just like the rest of us, Newman's older and more jaded than he was 20-some years ago. However, his appraisals of movies he especially liked or found interesting are as sharp and intelligent as ever. Newman is an intelligent and thoughtful watcher and he assumes his audience is as well -- he's refreshingly unwilling to embrace a consensus opinion, and to take "trashy movies" seriously. And he can be very funny.
In my opinion, this is THE single indispensable book for anyone even mildly interested in horror cinema.