Half-star average ratings would be good too. As illustrated by the comic above, 4.0 stars is not nearly as impressive as 4.5 stars! Seriously.
I would like to see ratings require a comment, like Amazon and the WordPress.org theme/plugin directories. The ability for the author to follow-up comment on a review would be good too in case some clarification is necessary. Transparency would be very helpful both to the authors for improving items and to potential buyers. Reviews are just plain handy.
Customers love videos. You can also make controls in the preview on the front end to let them sample color changing, fonts, etc. in real-time.
Just had my first item drop from 5 stars to 4 stars today. It’s not a very popular one so I don’t get a lot of feedback and nothing that would indicate anybody is supremely unhappy, so I think it’d be great if a small review was required for each rating. Otherwise, I have no idea how to improve this theme for my customers so that it’s worth 5 stars to them again. Love the Amazon review system. Even wordpress.org does this now and it’s great.
I use Media Temple (gs) for some smaller WordPress sites. I haven’t had any serious problems. The uptime has been good as far as I’ve noticed and I’d give the support an A. Not a bad price either.
Not allowing Extended licensed assets in themes will actually help Envato transition to full GPL for WordPress themes at some point in the future.