Why not? One of America's biggest enemies is dead. I know this doesn't end the war by any means, and it SHOULDN'T have any effect on how people view Obama's presidency, but regardless, it's a historic day in US history and I'm sure those who lost family in 9/11 or any other attack must feel a bit better.
I'll be perfectly honest in saying I really don't know shit about politics, but I think the death of OBL is definitely reason to be proud to be an American