It seems to slow down hugely after doing anything non-trivial (Chrome 5). It's not a hugely new idea, Oekaki boards have been around forever. Their execution is

It seems to slow down hugely after doing anything non-trivial (Chrome 5). It's not a hugely new idea, Oekaki boards have been around forever. Their execution is impressive though, throwing in a 'pro' version for free is something that throws a lot of people off, and paying for brushes is the real pay wall. I'd bet that combination builds a lot more fandom than the traditional approach. As far as the registration wall, I don't think the application itself is the biggest part of this product. The integration with dA and the community in general is what makes this worthwhile. Best of luck to them.