I like it. I think it's a progressive move so far as gaming goes. I especially like how people were all like, "WTF BOYKISSIN'!" to the ESRB and they were all like, "Yeah? What of it?"
I would've liked it more if they had incorporated it into the plot a little more. Not necessarily with Jimmy per se (as I think part of the reason it was left alone was so people who didn't want to acknowledge it didn't have to accept it as part of the canon), but certainly to a greater extent. As far as I remember, the only real canon mention of it was when you approach Trent and Kirby during the mission Movie Tickets. And even then it's not explicitly stated that they were on a date, although one can infer that by the fact that Kirby runs away first and he clearly doesn't want anyone to know he's gay since he always tells you not to tell anyone after you kiss him.
I also noticed a distinct lack of lesbians in the game, much to my disappointment. I could totally dig some Pinky/Lola.
I'd be careful about being too negative about it. Makes you look like a homophobe. People can get mighty ass chapped about their human rights and whatnot, even over something as silly as a video game.