It's in progress still. I have most of the code working, but it's not organized into the chapter structure, yet. I am planning to add a new chapter every ~month (I wish I could do this faster, but I also have some other commitments). Chapter 4 will be either uploaded by the end of this weekend or by the end of next weekend.

Depending on your level, it could take a lot of weeks to go through the already available material (code and pdf), so I'd suggest to purchase it anyway... It makes no sense to wait until the end, if you're interested in the subject.