I don't know what it was about White Cat, but I really, really enjoyed it. Probably because of the cats.
Not only did this book deal with cat(s), it also had fantastic worldbuilding and interesting characters. Curse Working is such a unique concept, and Holly Black did a really fantastic job introducing us to this new world. There was no info-dumping, but as a reader, I still wasn't lost. And the cons and crime families and political plays kept my interest the entire time. At the end, I was actually kind of freaking out, trying to keep everything straight and remember who had betrayed who.
Cassel, our male protagonist, is a pretty interesting dude. He has grown up in a family of curse workers, who can do things like manipulate luck and memory. But Cassel is an outsider; he is not a curse worker and it's something that has constantly set him apart from his family. So he tries to live a semblance of a normal life at his boarding school, while keeping his best kept secret: the murder he committed, which ended in the death of his best friend.
One of the things I really appreciated here was the way Cassel felt about his brothers. Objectively, Barron and Phillip seemed like total assholes who don't deserve all that Cassel does for them after the way they've treated him. But Cassel still sees his older brothers as men to look up to, even if he doesn't agree with what they do. Rather than completely turning his back on them, he allows the bonds of family to affect his decisions. I just loved his character!
Everyone else has already said pretty much everything there is to say about how fun this book is. If you're weary of a male protagonist, don't be. I found it refreshing, and loved the pointed writing style. If you love cats, then read this book! (Actually it doesn't really have that much to do with cats, but whatever).