I suppose that everything is a matter of opinion, but d3's syntax is the worst combination of obtuse (".enter"???), cute (the incredibly obnoxious chained api), and cumbersome (all the mutation, and the fact that d3 code always ends up being a long string of procedural spaghetti).
Of course, it does have a lot of useful code around math, projections, etc.
This project looks like a very welcome step in the right direction, showing that d3's great math can be used with obvious, declarative syntax.