It’s certainly a very nice looking site. Really quite pretty and smooth.
If I were to venture some constructive criticism though, I would say that it would be nice to have a way to manually change the SRS interval or the stage of items. As it is now, people who are coming to the site with some amount of prior knowledge will have to force their way through reviews or items that they already know well just to unlock new content. Although some amount of hand-holding can be nice, I don’t think it would be anarchy to allow a bit more manual control.
I do like the review process though. It will be nice, when I’m able to see more content, to see how the site handles vocabulary.