Mostly descriptive, as is often Lackey's tendancy. Very little action for the length. The Firebird appears for the first time around page 75 and is barely glimpsed, then does not reappear or speak till more than 200 pages in. I found Ilya uninteresting as a protagonist and have no idea what the bird saw in him. Weak, but mostly inoffensive, although there were a couple painfully stupid moments.
Read Brokedown Palace if you're interested in the violent-brothers aspect, Rusalka if you want vaguely historical fantasy with Russian mythos, or Magic's Pawn if you want something better but with similarities by the same author.