Having read some of Banks' SF, and then started reading his fiction as well, I still shied away a little from reading "The Wasp Factory". It says much that the bad reviews as well as the good are included on the sleeve, and while it may sometimes not seem as extreme as you might have been lead to believe that's more through the changes to our society and what is now considered acceptable in a work of fiction.
The story focuses on Frank, a 16 year old living with his father on a small Scottish island, part of possibly the ultimate dysfunctional family - all of whom seem to be to varying degrees insane. As Frank's horrific history is revealed, there's the prospect of an even more horrific future as his brother - lately escaped from a secure hospital - makes his way back for a visit....
Much of what you may have heard about this book is true. There are horrors upon horrors, it goes all out to shock at some points, and is definately not for the squeamish. The fact that it doesn't descend to being yet another trashy horror shocker is entirely due to the quality of the writing and Banks' unique way of hooking his readers so that one simply has to carry on and find out exactly what it is that he has planted the seeds of. There is much (very) dark humour in some of Frank's descriptions of the events he has participated in, and throughout there's the blackly comic undercurrent of Frank's assumption that he is in fact the only sane one in his family - despite all the evidence to the contrary.
Much is said about "the twist" and the brilliance of it, but I found it not nearly as startling as some others seem to have, and in fact it ends in an almost tame way - albeit, as with many a good yarn, with an open-endedness that allows you to think about what may follow.
Not a book for everyone by any means, and maybe not as fulfilling a read as some of his later works (especially Complicity) but nonetheless an absorbing, grotesque, horrifying, captivating novel.