Wow, doesn't it look pretty. Having read the various Tech information available the new version of Ultegra has surpassed the out going Dura Ace 7800 in every aspect.

If you have been following the current Tech coverage on sites like www.cyclingnews.com, you will see that the Team Mechanics have been mixing and matching from groupsets, not only in the Shimano but also from Sram and Campagnolo.
For many regular riders (and I count myself in this group), 6700 will come two months too late for this year. Why? Well this year's Etape holds a special draw to all cyclists, being the magical moonscape that is the Ventoux. Shimano could have chose to release it earlier, and for the increased sales in the 12-28 cassette surely would have been worth it on it's own.
With new Sram Force planned for a earlier release date (roughly) June, the second tier groupset war has just begun. With so many toys for your money at this price point, I would expect that ALL manufacturers (including the yet to be released FSA groupsets) to offer stunning value. Who will come out on top, that has yet to be decided. What I can sat is that wherever you decide to spend your cash you'll get a great bargain.