This is visually very interesting. You can tell that there is a lot of care being put into the transitions and all. It's a pretty competitive market out there in terms of "to do lists". With a good UI, it gives you a fighting chance. Sure it might not be for everyone, but that's the point. Segment the market and fight for your share.

How did you find backbone and D3. Do they play well together in terms of overall code maintainability? What worked and what didn't?