You're lucky that people are nice about it. That has never really been my experience. I tend to get weird looks or people will make very racist comments. I've had people say stuff about black people to me without realizing that I'm half black. I have also been insulted by other minorities for being of mixed race and for being so light-skinned.
No one has ever really told me I'm pretty because I'm mixed. The closest I've heard to a compliment is that I'm "exotic" or that I have an "interesting" look, but not that I'm pretty. Some people have a very stereotypical view of what a mixed girl should look like. Some people have told me that my skin is too light and my hair is too nappy, therefore I'm too unattractive to be mixed.
If anything, when I was younger, most people went out of their way to make me feel ashamed of who I was. I've only recently started to feel more secure in my identity.
You are beautiful, BTW.