I find this a very nice, informal portrait but I would like to suggest that you pay attention to verticals coming out of subjects heads; it can sometimes wreck an otherwise great photograph.
I agree about watching out for the "tree out of my friends' head" phenomenon, but in this case I don't find it too bad since it is soft and lines up with the natural bright line that divides his face. I think it helps that the overall background is light, so it doesn't stand out like a dark tree or telephone pole would.