I had a similar experience. I used it years ago, then I went back to it a little while back and ended up quitting for two reasons:
1. The gamification was too cutesy and annoying. And gamification works on me - I'm currently being held prisoner by my streak on another platform.
2. I didn't feel it was actually teaching me. I was being tested on words that hadn't been introduced. Trial and error is not a fun way to learn.