Originally Posted by Libertine

It's not an SEO theme - not any more than most others, anyway. The SEO bit is just a marketing line.

Its true value lies in it being a "set up a blog very quickly" theme. Change the header, change some borders, change some colors, and you have a simple, well-designed blog that's ready to go.

Some examples:

http://www.quicksprout.com/
http://www.twitip.com/
http://levarburton.com/
http://www.copyblogger.com/
http://simplemom.net/

All of these are based on Thesis, and most of them could be made very quickly.