First of all I'm not from the States, so I'm quite neutral on this "celebration" subject, still my opinion is subjective, so is my neutrality.
People celebrating someone's death doesn't scare me because it's generally the "simple" kind of people the ones that do that, the ones I expect to act that way, the mass. What got me a little bit nervous was the World Pollice attitude the USA government and the pentagon have over their issues.
I don't think Pakistan asked the USA for help in order to get rid of Bin Laden... but on a second thought if that guy was in my country I would allow a commando to take him out on the possibility of "forcing" the USA to make some Weapons-of-mass-destruction-Bullshit and bring war uppon us in order to kill one or two enemies (and getting "practical" on the subject), better having an small political/diplomatic scandal than being leveled.
Nevertheless, what still scares me is the impunity in which the US makes and breaks whatever they want as if they were some kind of supreme ruler with power over international law and sovereignty over the world.