I have been "genitally mutilated" since i was a young child.
From what i can guess, theres basically no change from being uncircumcised, though i have never been. Sex is.... well sex. Its not bad, but im not the kind of guy who will jump through hoops for it. My wife says shes not in the mood? I go play Dark Souls and Chill with my boy Havel for a bit. (Once you get past the whole "trying to crush you alive" thing, hes a really sweet guy)
Ive had times where i disappointed my wife ((Only happened twice, but it has happened)), and ive had times where im going long after shes ready to finish. I think it really all comes down to your level of sexual activity. Chances are you'll be just as good at it, or better, then someone uncircumcised based on your level of endurance.
In the end, a penis is a penis. Weather circumcised or not, sex is still going to make you happy (to a certain extent. Money makes me happier then sex. Id rather take 200$ over sex with any supermodel, because sex is a one time thing, and im the kinda guy who likes long term value). So, keep your head up, dont dwell on it, and if you end up being terrible at sex, blame your parents. I did that with driving, handling large sums of money, and dancing. I think being a good dancer is somewhere genetic. Short of a tangoooooo~ or a slow dance, i cant bust a groove to save my life.