this book is ok but schutz's book is better. it does a pretty bad job of introducing tensors, i think. some of the exercises are good but there are too many that are very routine. i only read the first 150 or 200 pages though, so i guess keep that in mind.
A bit outdated on the final chapters about Cosmology, but other than that found it a great introduction to tensorial calculus and general relativity. It does tend to give up on the exercises a bit toward the later chapters and just makes you do all the calculations that were skipped in the text.
My version of book was better than online pdf version available which have a problems in printing
This was the main book (theoretically) for my GR class but it is good for my for introducing k-calculus which I found it very intuitive way for constructing special relativity theory
But this was from books which leaves most work in derivations for you and this is the most thing i hate for a textbook.
Also hobson book is more useful and the problems is clearer there
It's a nice book which covers most of the important subjects in GR & Cosmology, the only problem is that lots of the equations are left to the reader to derive them in exercises.