I have been a WordPress developer and designer since 2005 and made hundreds of WordPress themes throughout the years. I have developed themes from the bottom, way before widgets and the flexible menu system where part of WordPress (old-time coding with PHP and HTML ftw).
I’ve used Kubric (the blue gradient design sent from the heavens :-)) and created child themes on top of it. Then tried hundreds, maybe thousands of free and premium themes from places like StudioPress, WooThemes, Elegant Themes, ThemeForest, Mojo Themes and many more. Hacked through a lot of those themes for my WordPress clients and learned a massive deal about what a good and a great theme look like.
Beside all my WordPress experience, I work with SEO and conversion optimization. That gives me a knowledge many other WordPress developers don’t have.