As long as it isn't,
"HEY! THIS CHARACTER IS GAY! HE'S GAY! LOOK! HE'S GAY! HE'S ACTING LIKE THIS BECAUSE HE'S GAY! IT'S FUNNY BECAUSE HE'S GAY! GAAAAAAAAAY! DID I MENTION HE'S GAY?!"
then I'm cool with it.
A character's sexuality should not be the sole defining feature of the character, and a homosexual character shouldn't be added just to have the token homosexual character there. If a homosexual character is in a piece, it should be because that's how the creator simply imagined him or her to be, just like how some characters are simply black, white, male, female, tall, small, and so on. It's just how the character is, but it isn't their only defining feature.
That's why it annoys me when people ask or demand writers, cartoonists, game creators, and so on to add a homosexual character to their work. The only reason that character would exist is to be the token gay character and unless that character was the stereotype of a homosexual person, no one would know that character was homosexual. That would be insulting.