I think your biggest challenge is going to be getting people to return after the first play. There are so many of these coming on to the market, it's hard to remember them.

NightCafe obviously has first mover advantage, and maybe you should think about implementing their style of gamification? They notify me every day with additional points, and even though I don't use them all the time, I will return there when I need a quick illustration for something.

Super congratulations on creating something which is really good.

[Edit: and it also needs advance and retreat arrows on the large view gallery option. At the moment you have to x out to go back and view the next image]