I have been building my own SRS flashcard web app, targeted specifically for language learning. Your implementation, UX-wise, is similar to mine (e.g. I have nearly identical "flip" transition"). Your use of icons is nicer, and the color scheme you chose is excellent.

I like the trade that you made of not having persistent accounts. I wrestled with that idea for a portion of my site that features "pre canned" decks. Without looking at the implementation I suspect it could then be a completely client-side solution served as static files.

Nice work.