D3 is a great product. We really like using it. D3 has a great integration with svg rendering, but we needed a canvas rendering which resulted in a merge of vis.js (guys did a great job on canvas rendering) and D3 (just the simulator: d3-force).
I tried it a bit and it does seem easier and it renders way faster
I see that it draws on canvas, and I used to draw on svg. This is awesome!
SVG excels at drawing a small number of large elements, where it sometimes performs even better than the HTML5 Canvas or WebGL.