IMHO it is a good thing that they are toothless. Otherwise we would end up with one world government. The U.N. best serves as a point for global negotiation.  The U.N. can organise collective action of member states. 

 We are on the same page not wanting a one world government. I don't know enough about the UN's policies and historical actions to say if they have been beneficial or if they have just maintained the status quo.