The New London Property Guide
"The New London Property Guide: The Only Guide You Need to Buying and Selling, Renting and Letting Homes in London" is a book, published annually (biannually?) which allegedly has good summaries of transport, amenities and the 'tone' of areas. It may be useful for someone moving to london.
It costs 10-13 UKP (Amazon has it for 10 and change).