Not all. I'm not uptight. I've tried it, it's just not my thing. However, if my man just couldn't live without it, I'd give up the back door... but it's just not a necessary part of our sex life.
I think the reason many women who try it don't enjoy it because they 1) have an inexperienced lover who just thinks you can ram the ass like any other hole and 2) don't truly relax, leading to a painful experience.