I am already working my way through this excellent book, so I'd like to add my welcome to the author - and say thanks for such a great introduction to machine learning with Python.
Incidentally, if people are interested in finding out more about the theory behind ML, I just discovered the
free online Machine Learning course taught by Andrew Ng of Stanford University (via
Coursera). I've signed up for this but missed the start date for the current session. I've heard very good things about this course, and you can check out the course videos via the
Preview link on the course website. So far it looks very interesting - as do many of the other courses on the site!