This summary explains why environmental impacts were not as great as they could have been. Location and prevailing currents made for a lucky break - there was plenty of time to prepare before the mess came near shore. http://en.wikipedia.org/wiki/Ixtoc_I
Depending on the location of a blowout in the eastern Gulf, plus winds and currents, Florida's coastlines and sea life could be damaged for a generation. See NOAA study here as to oil impacts on mangroves. The only mangrove communities in the continental U.S. are in Florida (the entire west coast of Everglades National Park) and the study explains in detail why this ecological community would be the very worst place any sized spill could happen. http://response.restoration.noaa.gov/book_shelf/34_mangrove_complete.pdf
Offshore drilling in the eastern Gulf near Florida could well be a nightmare waiting to happen. Both the ecology and the economy of Florida would be hit very hard by a major spill. The risk is too great - the rewards much too small.