The book just arrived today and it is a BRICK--1200+ pages. Dave and I decided to purchase it so we could get a head start on the lectures. If you have no interest in that, I'd suggest waiting to buy until you can get a look at one of our copies. As Dave says, it's not required for the class. And there's no way all the material will be covered. You should be able to do just fine in the course without the book.
I am in no way bad-mouthing the text. It appears to be very thorough. I haven't sampled the writing, but if Professor Koller can write as well as she lectures, it should be very clear. I only suggest that it is probably more than you need to get through the course.