Great initiative. More professors should do this; write your own material suitable to teach a course, and make it freely available.
What I also like is that if you find errata, you have a place to send them, with a reasonable expectation that they will be picked up in a new version.
What I also like is that if you find errata, you have a place to send them, with a reasonable expectation that they will be picked up in a new version.