I have a lot of issues with him on ideologies, but he was a GREAT wartime mayor. By wartime, I include the 90's when he simply wouldnt take any bull####, got the city cleaned, MUCH safer, invigorated the police force, saw a huge economic boom with many blighted or marginal areas becoming vibrant, very safe neighborhoods.
His ability to lead post 9/11 was remarkeable and a great success.
That said, by the end of his time in office, you could see the chinks in the armor. The very definition of great general, poor peace time leader.
His possible disregard for civil rights, his end justify the means approach - both of which are a bit magnified by his infidelities and HOW he handled them (look, people get weak, cheat, whatnot - but he really can and has acted an ###) and the aforementioned ethics questions create enough question and enough doubt.
I can not argue with the results he produced for some very difficult situations, but I also do not doubt that there are significant weaknesses in his person and persona - ideology and policy derived from that ideology just a part of that pie.
He is and always will be a cop. That can and has been a great positive. But I also believe it shades his decions, actions and behavior in a manner which would provide too much negative for the presidency.