I thought that BBM was an excellent movie. It had great acting, great directing, and great cinematography. It was really well done overall. =)
I saw this movie with my dad, and he was the only man in the audience. I saw it too long ago to remember if any of these women were gay, but I'm sure that some of them were. But I didn't have the experience that you did- no one laughed at the parts that you mentioned. I think everyone took the movie pretty seriously (not that's why those people were laughing, but anyway).
I am really glad that this movie was made. Because even with TV shows like Will & Grace and The L Word, being gay is still seen as being an outsider in RL. I think it's important for straight people (including myself) to see these types of relationships, because it helps to bring them into the "norm." And if having a same-sex partner is seen as normal, I think this world would be a whole lot better off. Of course... I'm not sure we'll ever entirely get there. But maybe even if we recognize that same-sex relationships are okay, then that would be making progress. Anyway. Sorry, I went on a bit of a rant there. =P =)