The gulf is a region of massive natural and now unnatural seeps, and it is well equipped to dispense of either type. The disperants kept it out of the marsh [and opening the gates of the Mississippi] and broke it up into smaller particles that allowed the bacteria to feed happily.
Corexit seems to be well proven even by the enviro's as better than crude oil, and without any DNA changing effects on life, or less than oil.
Not to say we should not take BP's billions for their f-up, or continue to study and make better dispersants.
New Yorker magazine. Latest one I think. The author started out as a mission to impeach BP, but learned that they did a good job after all the hype.
If we do not build more nuclear, better start drilling like wild today in the gulf.