Thanks for mentioning ThemeSorter. Right now our focus is to get "all" themes/sellers indexed in detail (while keeping up with new releases). I have figured that means about 1,500 themes from 50+ reputable sellers at the moment. A lot of work, but we're committed to this project (it has nearly become my full-time job).

After that we will focus on improving the features of TS, starting with reviews. And you bring up a good point with Amazon-style reviews. Along with strong search capabilities, that is of huge interest to users. The challenge will be how to get people to voluntarily spend time writing reviews. That can be tricky. ;)