Any time the characters who speak Russian come on the screen, I tune out until they show the English-speakers again. I enjoyed the Nina story line back before they shipped her off to Russia, but after that, I just didn't care about her any more. I honestly have no idea what's going on with her or any of the Russian-speakers...literally nothing.
Hopefully they'll shift more focus on the story lines I care about:
Elizabeth & Phil (marital problems, conflicts between American vs Russian lifestyles, juggling spy career with parenthood, etc)
Paige knowing the secret
Pastor Tim
Stan secretly spying on Elizabeth & Phil
Phil & Martha
Martha getting uncovered by the FBI
Conflicts between Phil & Elizabeth and the Center and their handlers
The spy story of the week
With all this going on, I don't think we need the Russian plot lines to fill out the show.