Russian's course effectiveness
I tested the course and found it enthralling at first. My only problem is that the start of using questions and phrases should be second after alphabet practice, not before. I know the alphabet and some basic russian, so I can write the latin translation which I found was also correct. I like that and I will soon include the russian keyboard on my desktop. I find that this course is having a shaky but productive start and I applaud the team at hand for building this most likely difficult course in Duolingo. Spasibo and good night.
From my own experience, you learn a new writing system best by actually using it. Of course you should go a bit slow on the grammar in the beginning but you shouldn't avoid it entirely until you memorized the writing system perfectly.
Just learning the alphabet without using it in simple sentences was the most boring thing I did in language learning. I tried it with Cyrillic (when I just started to get into language learning) but it didn't really feel natural until I used it. When I started Japanese, I didn't even bother about learning the writing systems. I just started to use hiragana and katakana (almost 100 different characters) and while I often had to check things, it went a lot smoother than my initial tries with Cyrillic (merely 33 letters in Russian, I think). Memorising the new writing system not as an isolated thing but embedded in the language you want to learn proved to be much more effective, at least in my case.
I'm really happy about their choice to combine alphabet practice with a few simple sentence structures.