Obama says this is going to be an incentive for mass Al-Qaeda "recruitment bonanza"
Interestingly, he has the most mild opinion of anyone the article quotes:
http://www.bbc.co.uk/news/world-us-canada-11243711
Interpol: "If the proposed Koran burning by a pastor in the US goes ahead as planned, there is a strong likelihood that violent attacks on innocent people would follow,"
President of Pakistan: "Anyone who even thought of such a despicable act must be suffering from a diseased mind and a sickly soul...It will inflame sentiments among Muslims throughout the world and cause irreparable damage to interfaith harmony and also to world peace,"
British Government: "We would strongly oppose any attempt to offend any member of any religious or ethnic group. We are committed to religious tolerance,"
Hillary Clinton: "disgraceful"
General Petraeus: Endangers the lives of soldiers.
Apparently, the Vatican and NATO also disapprove, but no quotations were given.