I haven't been following this case much, but my biggest bone to pick is with Zimmerman is himself "playing police officer".
Law enforcement are often degraded and disrespected, but if he was a Law enforcement officer, I suspect this situation would have been handled much differently, even if Trayvon didn't know he was dealing with an officer of the law. Most law enforcement officer's require some MMA training for a purpose. If you aren't highly skilled in MMA, and can't defend yourself, you have no business being a "town patrol officer", let alone pursuing or confronting an individual.
It doesn't mean Zimmerman should have been found guilty (according to current laws), but he is no doubt a fucking douchebag and an irresponsible citizen for appointing himself as a watchdog with no other means or training to defend himself besides a lethal weapon.