We just finished construction of a new store for Faith Life Now. You can check out the finished product at: http://faithlifenow.com/store/.
This is our first D7 site of this scale. We had to rewrite several Ubercart modules so they would work correctly in D7 so we spent a bit more time on this than we would have if we had used D6. However, we felt it was worth the extra time due to the many new and improved features of D7.
We would love to hear what you think.