Various Islamic sources have said it was legal. It is true that others have criticized the burial. Islam is not the monolithic all believe the same thing that many in the West believe.
Just as with Christians you will find people on both sides of the issue on just about any subject.
Personally I believe they were both clever and wise to have buried him at sea.
I don't care for the policies and agenda of Obama. But his follow through on what Bush started with Osama deserves kudos. Well done!