Any religious based government (including christians) that takes a collection of literature from Antiquity and base their policies on it near enough word for word is something to be feared. (No bombs for any of them)
Any government who forms their policies around the fact that they have a bigger stick to hit you with than you do, whether the policie is benign or not is something to be feared. They have the bomb and say that it is a good thing that they do, but the bottom line is that they would use them if the situation demanded and condemn us all.
I would rather not see Iran attain the nuclear bomb, though it is inevitable that someday they will possess such an item and so will other countries that some deem to be unsuitable for such technology.
The U.N is a worthwhile orginisation, however, an orginisation that forms decisions based on the political stance (at that time) of individual countries, rather than what is best for the world as a whole. The U.N is comprised of many countires but it is only 13? that have the real punch over issues of enforcing U.N resolutions and suchlike.
These resolutions aren't worth the paper they're written on if a country decides to ingnore resolutions, or so it would seem in the case of Israel and if a country dedides to work outside the constrains of U.N law then they are capable of doing so, as in the recent conflict in the gulf.
So I think the question shoud be, once they do get the bomb what will we do?