Lectures in Logic and Set Theory. Volume 1: Mathematical Logic

My opinion is that this is the most readable and user friendly advanced book on Set Theory today. Especially the treatment of (Cohen's) Forcing is valuable, since other expositions on this subject were not suitable for beginning graduate students (Kunnen - very good, but very sophisticated, Jech - also good, but presents Forcing via Boolean Algebra, which is less widely used today, and the book is too long as an advance introduction). Also the style or writing is inviting, and not intimidating. Very significant book, pedagogically.