I'm currently using it. I've tried it and stopped using it twice earlier. I was using it to study kanji, Lojban words and mathematical definitions, all of which was basically learning the vocabulary of a language I didn't actually speak. After some months, I got fed up from the feeling that I was memorizing what seemed to amount to mostly nonsense when I didn't have a routine of trying to learn to read and write the languages or trying to do math in the side. I also didn't like the Anki interface for entering new cards that didn't let me do card batch processing easily and the fact that the card database was stored in an opaque binary blob.

I'm currently using a text file as the card source and have a starter deck with quotations, historical dates and other fluff that's reasonably meaningful as stand-alone. I've been reviewing the deck since last December, so it's still too early to tell whether this one will last.