I can see where she can be dislikable. She's got to stop the show to get attention. She's all about makeup and fashion and pretty things.
But she's also hardworking, and willing to go to any lengths to get what she wants. She's uncomprimising, and the one time she does comprimise, she's clearly uncomfortable with it. I think she's honestly a great role model for little kids. Women in todays society often give up things they want for their families.
I loved her "relationship" with Prince Blueblood. He was royalty, but a douche. She saw that, and while it took her a while, she figured out he wasn't actually what she wanted, no matter his title.
Yay Rarity!