As long as the Security Council holds the real power in the UN and the USA remains a permanent member with a veto, the rest is OK. We (USA) will never get a better deal in another international organization than the one we have right now with the UN. Regardless of the anti-American rhetoric in that place, the USA has a permanent veto and when the chips are down, can stop the UN in its tracks.
The UN is an impotent organization and can only hamper any future military actions that the United States might have to take to protect our own(and the worlds) security.