Most don't hate him anymore. They just hated him during his MS days because back then he proclaimed that he wanted to kill everyone in Konoha and crush their dreams, including innocent people.
Why people don't like him now?
-He doesn't care about the consequences of what he does. Some people are annoyed by this...others like that he doesn't give a f***.
-He's rude
-He treats people like tools, if you're not useful in his eyes, he will not interact with you
-He's arrogant
-He cannot admit his flaws...but this isn't a problem because nearly no one else in this series can do that either for some reason. :/
-He acts like he's the only one that's suffered in life and believes that he has suffered more than everyone, when he has not. (Though, he has suffered quite alot.)
As for my opinion, I don't really hate him or care for him. I'm just indifferent towards him at the moment. I think he was his best during his Hebi Sasuke days, back then I was a fan.