Dude is correct. def! you can find me here @roykolak. No not many users, tho just lunched it a week or so ago. You can read about the motivation here: blog.milkshake-island.com/post/75288447289/building-for-the-right-reasons
Mine also works on mobile, does yours?
I don't think there's much demand unfortunately for postcards that weren't handwritten which is the sad thing.