There are so many reasons i dislike her. She's a very bad character in my eyes, but that's because Kishimoto made it that way, she at least had potential. As someone on the first page said, i could also make a PowerPoint presentation of her flaws, but that's just digging in too deep.
I guess a major impact on my judgment is the fact that i dislike her personality - it's not that i don't like the shy girl, but she's just... so... bland. Everything, everything in her world revolves around Naruto. Cousin died a minute ago - "Naruto-kun's hand is so big and manly". Bleh. She's literally the same character from Part 1, aside from some confidence gained (thank god, or else she might not have participated in the war or lost to the first White Zetsu that taunted her or something).
I'm no fan of Sakura either, but at least Sasuke isn't mentioned every single time she is shown. Hinata is probably the female i dislike the most in the entire show, and is among my Top 5 dislikes.