My Take
Overall, I really like Khan Academy as a teaching tool. The material is explained clearly and cleanly in the videos with Sal Khan's neat handwriting and drawings to further explain.
How I Use It
I would use Khan Academy as a way to either introduce new material before I go into depth in class or as a way of review for students after I teach the material during the class period. The short quizzes and tests after the videos are a good way to test how much the students understand the material and what needs to be further explained, while also providing them with extra practice.