I've always found working with Raphael a little bit undocumented, and it didn't quite go far enough for what I needed.
The syntax of D3 makes my head spin every time I try to use it. It's almost too powerful for simple things.
I used Raphael on Cryptographics and while I was doing it I wished there was something that felt a little more friendly. This looks like a promising alternative.
It's become pretty clear to me that the gold-standard for SVG manipulation on a page is D3: http://d3js.org/
This seems to take a more designery-approach to things, but I don't see it doing anything D3 doesn't, and it seems to be lacking in a lot of the things that make D3 great. If you're gonna learn a syntax for SVG manipulation, might as well be one that unfolds the world for you, instead of one the limits you, I'd think.
I have to say I find D3 (as well as its predecessor Protovis) a little hard to digest. I'm not sure if it's because of its approach or syntax, but I always had troubles figuring out how to chart my data with it. I do understand it does pretty cool stuff, though.
On the other side, Snap.svg seems to be quite designer-friendly. The syntax Dmitry (which by the way is the guy behind Raphael) is using is a plus: it's closer to jQuery, thus making charting slightly easier for the average designer. I can only speak for myself, of course.
Love seeing Brackets in their demo video.