I really liked the first book, The Bear and the Nightingale. I loved Vasya, the girl who sees spirits and can't be tamed to fit the role expected of her; I loved the evocative, wintry, oppressive, vast Russian setting, and the way the folklore is entirely integrated and believable. Of course there is a frost demon! How could there not be? I loved the family dynamics: complex, deep, hurtful, healing, strong, strong bonds. I hated/loved the twisted priest and the way his view of the world influences everyone in ways Vasya simply can't fight, and the way she chooses to fight anyway.

The relationship between Morozko and Vasya is brilliantly suspenseful, and the development of his character is one of the highlights of the novel. I'm not going to say any more, but there are some lovely bits.
So, we've got Wo/Man vs Nature and Man vs Himself and Woman vs Expectations, and then Vasya encounters some burned villages and decides she has to do something about the whole Man vs Man thing that's going on with those darned Tartars. And she's disguised as a boy, so there's lots of Lies vs Truth vs Being Found Out (I know that wasn't one of the standard high school Conflicts, but it's one anyway), and she ends up going to Moscow and getting pulled in all sorts of directions. (Wo/Man vs Society). Then a bad guy worse than the priest shows up, so there's seriously Wo/Man vs Evil.
All the conflict and tension you could possibly pack into a novel, continually ratcheting up in a lovely slow build, layer upon layer, and all the way through you are feeling the bite of the frost, hearing the crunch of the snow, smelling the smoke from the fires. Inhabiting Vasya and her world. There were times I had to put the book down because it was getting too intense. At one point I shouted out loud.
And I haven't even mentioned Vasya's family, who are wonderful, and who love her, and who are several of the directions she gets pulled in. And by the time the Firebird showed up my brain melted down and my heart exploded.
So, yeah. I think you should read this one. Cannot wait for the third book!
Osso Bucco (I know it's not Russian: you can substitute your favourite Russian stew if you want): meat falling-apart tender and satisfyingly chewy, sauce savoury/tangy with a hint of sweetness, every bite making your eyes roll back in your head a little because it's so perfectly, completely delicious.