After trying unsuccessfully to merge features from two different themes, I was about to give up, until I found this.
Even though I'm a genius, it's incredibly difficult to merge complex themes for different sections of a site. Even after dequeueing and enqueueing stylesheets based on category, merging widget areas in functions.php, creating independent templates and loops for different post types, etc. my site was still puking all over the place.
This plug in accomplished what I wanted with almost no effort. It truly wowed me to see it working so quickly.
The only feature that would really make it - the ability to set entire post types to default to a particular theme. Setting the theme for each post is a tedious extra step. I hope development continues on this plugin because there's nothing else like it. 5 stars.