LGBT themes are definitely fine with me!
Explicit sex scenes where the author walks you through every single little thing that's happening make me uncomfortable, so I'm not a good person to ask for feedback on that kind of scene. But that's about it for what makes me uncomfortable.
I'm glad you brought up content, because my story has some really dark stuff in it: lots of blood and violence, several uses of the F word, and at one point, a character implies that he was sexually harassed.
EDIT: I forgot to mention, there is use of tobacco in my story as well. And drugs are mentioned.