1. It is always updated, not leaving users in the lurch.
2. It uses a "child theme" system. A child theme formats the main theme, without you having to touch the main theme. The reason this is good is because it means there is no danger of the user mangling it in order to customize it. This allows for the main theme to be improved or updated according to changes in wordpress. A child theme can be formatted pretty much any way you can imagine. You can experiment without fearing that you've totally wrecked something.
3. Support is excellent. I've gotten timely, useful, and applicable responses and solutions to various questions I've posted. In contrast, other forums (including those for expensive themes) often leave you in the lurch.
4. It is versatile with widget areas in every location you may desire.
5. It allows for easy control of the formatting of specific pages or posts via style.css.
6. If someone wants to learn Wordpress and how to fully take advantage of its functionality and potential, and you want to learn a little about WP coding, ThemeHybrid is unsurpassed. It is a great forum to learn to do so.
7. It's got lots of range and functionality.
8. It is free except a yearly fee for support.
It is not necessarily the most idiot proof theme out there. If you want easy theme and everything controlled from admin panel, it may not be the right one for you (nor would be expensive Thesis theme).