Why is it a big deal that Via read War and Peace?

Via's father is proud that she is reading War and Peace by Tolstoy. In fact, it is something he boasts about to anyone who will listen.
Tolstoy's book is more than 1,000 pages long and is not typically the kind of book teenagers favor. So, it is a "big deal" that Via finishes War and Peace in this novel.
As for Via, she has always been the daughter her parents could depend on. Most of the time, Via's parents are preoccupied with the welfare of Via's brother, August. As a result, Via has always figured things out on her own. She always stays ahead of school projects and is generally capable and independent. In fact, Via's parents agree that she is old enough to take the subway alone. A fifteen-year-old who can appreciate literary fiction by the masters will be more than capable of navigating the subway system alone, they decide.