It's one of the very few role playing games that I don't like.
I find the system to be wonky, the setting to be boring, and the players to be arrogant. (...not really, it was just a nod to the YB! players of the board

)
More seriously, I hate the basic resolution mechanic of the Storyteller system, which creates weird statistical quirks that make calculating probabilities very difficult (and which make the system unusable with very high or very low difficulties). I don't want to know exactly the % of succeeding at some check, but the system makes it hard to even understand what a certain score means. The flavor text in the skill description doesn't even get close to what the actual mechanics of the game create, so it doesn't help. This is also a sever hindrance for the GM, who may have troubles deciding a reasonable difficulty for something.
The other thing that I hate is the obsession with statting the character's mind (humanity, courage, willpower...). I don't like having a dice roll tell me what my character wants to do. Especially since, what with the wonky statistical model, the dice roll often makes my character look like a crazy lunatic.
And then there's the setting, which in all WW settings I've read tends to look very cool from the core manual and then roll downhill into complete silliness once enough supplements are introduced.