People hate Sakura because they are too childish to let things go. That and they try to blame Kishimoto and say that he portrayed her the wrong way, when they don't even understand how he tried to portray her. She was never meant to be bad*** or whatever. He said that he wanted a normal, relatable character and that was her purpose in the series. In pt1, her personality wasn't that bad, considering she stopped acting like a snob after the Zabuza arc...unless you watch the anime of course, because they do usually show her in a bad light in fillers for some reason. :/ That and in pt1, she was 12-13. She was a normal person and normal people are annoying. She was nice to Naruto back in pt1 as well and she only hit him when he did something wrong. To say that you hate Sakura for hitting Naruto is truly a cheapshot, when we all know that it is comic relief, he is completely fine after max 14 seconds, and Naruto himself doesn't mind. Sakura doesn't trust Sasuke anymore, and it really doesn't seem like she loves him any longer. She was weak in pt 1 (obviously...she was the only one from a civilian clan) but she is now the strongest female character. Sakura improved and matured throughout the series. Not really any reason to hate her character at this point. If you deny that, then you are just pathetic.
The only problem that I have w/ her character is that I think Kishimoto should have written more fights for her, but that's pretty much all. In the emotional/mental department, her development is just fine though. For this series and compared to the other females, she's the most well-written female. Which is slightly a given, when the only other females in the series who have relevance are Kushina and Tsunade. And Kushina hasn't been seen in more than 10 panels and Tsunade is Sakura's master.