Probably more of a 3.5 stars. It's got some really great info on the biology and mechanics of the knee, along with some good exercises (I believe that all of the ones my orthopedic surgeon prescribed to me are on the list). But I almost recommend this more for people who have chronic knee pain, not for people (such as myself) who twist their knee in one accident and tear a ligament. Also, if you don't have access to a pool (and one with varying heights), a large chunk of the book is "useless".
Also, it's weird how the authors seem to assume that the readers know almost nothing about the internet and the changing medical practices (mainly when talking about PCAS). It almost seems as if the authors are assuming the audience is mostly 50+??
Still, it's got some good info and makes you aware of what to expect when you visit your doctor or get an MRI.