Thesis 2.0 is DIY Theme Framework for faster website and theme development. It is not just for faster development but is also fastest to load in comparison to other theme frameworks. Thesis is designed mainly to be used for blog and magazine themes, however, you can push it forward if you really want to. It is not as customizable and complex as Canvas Theme Framework but no everyone needs fancy features that no one will use.
Thesis is one of the most popular theme frameworks and is used for thousands of top bloggers. It has this special aura that makes bloggers to choose this framework and then stick with it along the way.