After having looked at the free version of that book
http://xxx.lanl.gov/abs/gr-qc/9712019
I must agree and recommend you this apparently excellent piece of work! You should buy the commercial version of the book because
- it has better diagrams
- you will help Sean to be awarded for his work
http://www.amazon.com/exec/obidos/tg/detail/-/0805387323/
Update: When I was telling about this recommended GR book to Andy Strominger, he replied: "I am using it in my course!" :-)