Sasuke is annoying because he's an idiot.
A BIG idiot.
His two main aims are to revive his clan and kill itachi. Logically it'd be better to become the best Shinobi he could , reproduce and THEN kill Itachi. Sasuke also seems to ignore the fact that to repopulate his clan he'd need to have LOTS of sex with several females.
Instead he learns ONE vaguely decent attack Jutsu and then goes ape-shit when his Brother arrives.
Tool.
Why I hate sasuke:
1. At this point, he's way too strong
2. Kishimoto is a Sasuke fangirl, might as well change the title to Sasuke.
3. Late Night Training Sessions with Orochimaru.
4. Shirt is open, easy for orochimaru to slip his hand in.
5. Sasuke literally has snakes coming out the wazoo.
6. Completely blows off Sakura for Orochimaru
7.Angst, too much angst. Really, IMO, Kurapica is Sasuke done right.
8. I hate my brother, so I'm going to become just like him.
Really, most of that comes from, as fox says, Sasuke being and idiot. Even if he kills Itachi, itachi still wins out because Sasuke became what he wanted him to become, and did what he wanted him to do.