Bill mixes a lot of different topics on his blog outside of the stock market. The posts about the stock market though are unique because it is one of only a few websites (and one of the best) that attempts to mix the best qualities of various styles of investing to achieve success as opposed to relying on only one methodology.
One of the best things I like about Bill's blog is that any stock market question or problem you might have Bill can offer a quick understandable mathematical formula to help show you how to solve the problem. To paraphrase a movie, Bill is just "wicked smart." He is so good at math I think that if I ever met him I would throw a box of matches on the floor to see if he could count them. Seriously though, in my opinion Bill's blog is one of the most intelligent bodies of work you are going to read for free on the internet and learn something.