'The Full Rudy', an article in The Nation by Jack Newfield, is one place that provides a balanced assessment of Giuliani.
At this writing it seems possible that he will become the Rep nominee.
In the writer's opinion, it will be a disaster for the United States if Rudy takes the presidency whether the win is legitimate or not.
In the event Rudy is the Rep nominee then the Dems need to do a full swiftboat on him - he should be buried so far that he has zero possibility of recovering. He has publicly appealed to the same anti-American, base instincts in the electorate that propel the Bush administration toward dictatorship. His record in New York is one of incompetence and vitriol.
Conventional wisdom is that negative campaigning works. If Rudy is the nominee, the Dems need to swallow their distaste for negativity and smear Rudy as hard as they can, IMHO.