We don't know all the facts and I think it's reprehensible than anyone was killed. Zimmerman certainly has some issues he needs to deal with...but there has definitely been a media bias out there with how these two have been portrayed. Zimmerman's picture in the media is usually been one where it looks like a mugshot of a felon and Trayvon's has usually been a picture of him as a clean-cut, cute looking kid from years ago, not the tatooed 6'3 guy that he actually was at the time of the killing.
If Zimmerman is guilty of judging Trayvon's character based on his appearance, a lot of the media and people who have made judgments on this story based on media bias are guilty of that as well.