Now, I have mixed feelings about Osama's death.
On the one hand, by killing him, more lives will be saved in the long run, you know what they say, sometimes the needs of the many outweigh the needs of the few.
On the other hand, he was just a very confused man who happened to have a lot of power. Also, his son was killed as well. It wasn't the sons' fault, his Dad gave him a biased viewpoint and he never heard both sides of the story. He probably thought he was protecting his hero father from the 'Evil American Capitalist Pigs.'
Yes, I am sorry that he is dead, I think they could have just tranquilized him, sent him to a maximum security prison and used him as bait for the other terrorist forces that would be loyal to him. Then, they would have quite a few terrorists behind bars and there would be no bloodshed. Plus, the terrorists would be less likely to do anything drastic because the Americans captured him, not killed him.
So, yes, that is my opinion on the matter.