Oh dear. What a loaded question. If you say yes, you sound vain, which is not a character trait anyone aspires to! But one the other hand, you've got to admire a woman who is confident enough that she could describe herself as beautiful.
Beauty is a funny thing, because, as I'm sure others have said, it is somewhat subjective. There are some basic beauty standards that appear to be universal, however; for example, facial symmetry is appealing to everyone. Women tend to have proportionally smaller noses and jaws than men, and proportionally bigger eyes; these features work to make a woman's face more attractive, as long as it is not taken to the extreme (i.e. bug eyes and a receding chin). I suppose, if pressed, I would say that while I am not exactly beautiful, most of the time I feel quite pretty. "Cute" is probably the best word. For what it's worth, I'm happy with what I look like. And as we all know, the beauty on the outside is much less important than the beauty within -- and of that, I am no judge.