This service is a great concept but needs some options. The way I put things into memory is by recalling them right before they fade from memory. To do this there needs to be a trigger. So if I’m learning french, for example, English is the trigger, that helps me recall the french. The flashcards currently show me french first and tests my comprehension in English, so I would prefer to reverse that.
Also being aware of what’s fading from memory is very useful so having all cards presented in front of me with the ability to click and flip each one of them, and the ability to move and reorder them would make the learning experience perfect.