Well, I had no problems with the other characters, either. I liked them myself. In fact, Trevor is supposed to be a psycho basically, but I'm most looking forward to playing as him because of that fact.
Then we probably play these games for different reasons.
I like to identify with the characters, and when they are written and acted well, that's going to be no problem.
I could easily identify with CJ, I couldn't with Niko Bellic.