So the book is about four people who have independently decided to commit suicide (not as grim as all that).  They accidentally meet on the roof of a building from which it is popular to jump in London.  It takes off from there.

The characters are disparate.  I was surprised that he got them to work together.  At various points in the book you sympathize with each of them.  I recognized two of the characters as reflections of previous characters he has used in other books, JJ is from High Fidelity and Martin is from About a Boy.

It's a book that I would recommend, though not highly.  Unlike his previous books which were definitely for males, I think it is an equally good read for both men and women.