Both better and worse than I expected. 
Probably improved by a certain level of nostalgia having read this for the first time probably about 6 or 7 years ago when I would have been about 14 and completely obsessed with Marilyn Manson. But I will admit it's not the best written thing on the world (and the more recent history of both Manson and his ghost writer definitely didn't give me a particularly favourable perspective). 
The last chapter is probably the best - clippings of outraged interviews and leaflets distributed by infuriated Christian groups interspersed with Manson's diaries made for a seemingly more honest account.
The little details of the circles of hell being mentioned when relevant, the well placed photographs etc. were also pleasantly interesting and made the book seem more polished than certain bits of writing might suggest.