The wars between IT-methodologies do not calm down. Every several years we receive absolutely new, quick, simple, and effective methodology. It finely should solve the main problem — the creation of the qualitative software on term.
I think that the single truth concerning methodologies is that they do not exist at all.
There are only successful project solutions (SPS). That can work (or not) in a particular situation. The goal of this book is to offer IT-community to find and classify them.