Hobson [, Efstathiou and Lasenby] was the book I used to revise for my exams, and that was good. It's not overly simplistic and requires a bit of working to get

Hobson [, Efstathiou and Lasenby] was the book I used to revise for my exams, and that was good. It's not overly simplistic and requires a bit of working to get through the maths, but it's comprehensive and goes further than most undergraduate courses do (up to Kerr black holes and a bit more).