XII get's so much slack for being one of the later games in the series. It falls into that "everything after ( x ) title is crap" people whine about.
To me, XII was the first truly good FF since VI. Don't get me wrong, I LOVE VIII and IX, but they were both kind of mediocre story wise and focused heavily on a love story. Both villains were also 'evil' but in a way that still made you kind of like them because you can almost understand WHY they were that way.
Vayne Solidor is just a dick. He's a sadist evil bastard and I feel righteous every time I kill him. He's the first viliain since Kefka were I finished the game solely so I could destroy him. But you know what? I love Kefka and Vayne for that reason; they truly fulfill their roles AS the majour bad guy.
XII also had a complex cast of characters that all had so many layers to them; and each were explored in the game. There was no: This character is deep because of the way they stare away from the camera and be gloomy all the time. Each and every one of them had background and interesting stories that promoted their character types.
Even Vaan has grown on me. He's finally a 17 yr old that ACTS like a 17 yr old: Somewhat dreamy and spacey, just wanting to do what they want and not being told what to do and also a bit naive when it comes to the rest of the world. People seem to hate on him for these traits, but I find it makes him a wonderful character. The fact that he has the capacity to be angry and blame Basch, but also is able to confront the situation and learn to hold his feelings aside to get through the situation (and eventually hear Basch out and actually understand who Basch is as a person and forgive him) is something I find they tried to get Hope to do, but Hope failed miserably at it.
I could write a thesis paper on everything about XII I like, but I don't think anyone has the time.
TL,DR; XII is complex and a return to actually villainous villains. Vaan acts his age. Hope's anger at Snow is just a badly done version of Vaan and Basch.