I would still recommend it, even to those who know how to program. A lot of the book is just non-stop typing as fast as you can. The benefit to me was how it improved my 'muscle memory' when actually sitting down to write something on my own. There was less stumbling over little things like -- "how do import a library again? 'require?' 'load?'"
As with most things, you get out of it what you put into it. For example, I wrote unit tests in one of the 'extra credit' assignments to explain a bunch of python's symbols.