A First Course in General Relativity is in my opinion the best book for those who are learning GR for the first time. It does not pretend to be mathematically rigorous by definining manifolds, a common attempt that invariably distracts the student away from the underlying physics, and is often utterly wrong when the author is hardly a mathematician him- or herself. The book also covers everything essential for the student to understand what GR is really about, and offers a lot of interesting problems that are hard yet solvable. The only prerequisite for this book is calculus and Newtonian mechanics, although the student should be very good at mathematical reasoning.
Despite all these advantages, the book is not without errors, some of which are rather serious and themselves very good reminders that one must be very careful with the implicit assumptions valid only in Euclidean geometry. Certain parts deserve more explanation than it is easy to show that ... as one could in fact easily "prove" the right result in the wrong way. Also, the incompleteness of the official solution manual makes the book less approachable for students without easy access to a professor.
For these reasons, I have decided to publish my own versions of Errata, Notes, and Solutions for this wonderful book. I hope the reader will find them helpful.