I know a lot of people (myself included) are happy that Bin Ladin is no more.
There is a disturbing article from Reuters that the goal was to kill, not capture Bin Ladin. I'm not certain, but believe this is an extra judicial assassination. Either an assassination or a war crime, take your pick. I know many were not happy when Bush was invading Iraq. I'm uncertain if our President, on his own authority, can or should ever order a summary execution of an individual. It is doubtful Bin Ladin would surrender, and it is for the best that he is gone. However, establishing a doctrine that a President can kill someone via our military without any judicial or other process (than his own judgment) seems dangerous to me.
My concern is Obama may be targeting and killing people, who could be taken alive for trail and debriefing. IF Obama is killing people to avoid repopulating Gitmo, I believe we have a war crime. If not, then it may just be a debate about what is a war crime. I know when Bush targeted people, many news stories were published about armed drone use as being a war crime.
The story is here http://www.reuters.com/article/2011/05/02/us-binladen-kill-idUSTRE7413H220110502 
(Reuters) - The U.S. special forces team that hunted down Osama bin Laden was under orders to kill the al Qaeda mastermind, not capture him, a U.S. national security official told Reuters.
"This was a kill operation," the official said, making clear there was no desire to try to capture bin Laden alive in Pakistan.
Regardless of the figures used, the case that extrajudicial killings are justified is extremely weak, and the number of civilian casualties is far too high to justify their continued use.
A further twist to the Obama Doctrine is the breaking of a taboo that the Bush administration balked at – the concept of treating US citizens outside of the US constitutional process. During the Bush era, the treatment of detainees such as John Walker Lindh, Yasser Hamdi and Jose Padilla showed reluctance by officials to treat their own nationals in the way it had all those of other nationalities (by, for instance, sending them to Guantánamo Bay and other secret prisons). The policy of discrimination reserved for US citizens showed that there was a line the US was not willing to cross.
At least, today, we can strike discrimination off the list of grievances against the current president. The National Security Council of the US has now given specific permission to the CIA to target certain US citizens as part of counter-terrorism operations. Specifically, Anwar al-Awlaki has been singled out for such treatment, as it has been claimed that he was directly involved in the planning of the Major Hasan Nidal killings and the Christmas Day bomber attacks. Indeed, it is claims such as this that bring the entire concept of targeted assassinations into question. The US would like us to believe that we should simply trust that they have the relevant evidence and information to justify such a killing, without bringing the individual to account before a court.
The assumption that trust should be extended to a government that has involved itself in innumerable unlawful and unconscionable practices since the start of the war on terror is too much to ask. Whatever goodwill the US government had after 9/11 was destroyed by the way in which it prosecuted its wars. Further, the hope that came with the election of Barack Obama has faded as his policies have indicated nothing more than a reconfiguration of the basic tenet of the Bush Doctrine – that the US's national security interests supersede any consideration of due process or the rule of law. The only difference – witness the rising civilian body count from drone attacks – being that Obama's doctrine is even more deadly.
Another discussion contrasting Bush and Obama doctrines is here http://www.guardian.co.uk/commentisfree/cifamerica/2010/apr/11/obama-national-security-drone-guantanamo