I honestly don't have a huge issue with this. I mean, it's dickish that he videotaped and put it online, but the act itself is fine in my book.
He wasn't running around Africa just shooting the largest thing he saw, it was a trouble elephant with a history of destroying crops and hurting people. On that note, he killed it pretty humanely, he took it down in two shots, a pretty remarkable feat.
I can understand people who have issues with it, but I don't have a problem with it.
But hey, I'm odd.