I love it.... I don't know if I'd want it be my name though. I really don't. It's like on the border between usable and unusable. If I met one I'd be super excited though. And as a middle name it's perfect.
I think Oakley is nice as well but if you used it you would like you were just following the trends rather than expressing your fervent love of trees. I babysat a little boy named Birch once... his parents were hippie-ish.
http://www.behindthename.com/pnl/87410