I just now finished up the book, although the last lesson seemed to be about abstract proofs, which I just kind of skimmed over. By the way, Pat Malone (local POP member with phd in math) doesn't like the way the authors of my calculus book teach math -- he says they sacrifice seeing the beauty of math for drilling how to work problems. Maybe I would ask him about any multivariable math textbook before going all the way through it, or just order a used one that he recommends.