I've taken both Busuu and Rocket Russian. I feel that I'm making more progress with the Rocket program. I'm being pushed to read it, listen to it, speak it and write it. Busuu didn't push me as hard, however it did let me interact with native speakers in Russia and the other former Soviet states, who corrected my lessons. I could have gone as far as I wanted once in contact with those speakers. However, without the grammatical structure in place, I found it very hard to try speaking or writing it. But I'd have to say that the immediate feedback on my pronunciation in Rocket is something immensely valuable and I love being pushed to write it as well. With so many ways to review and refine, it really cements the language into my 67 year old brain, which already has mastered Spanish, achieved a working knowledge of French and German, and now, the piece de resistance, Russian. Luvin' it.