Yes, he's not perfect in his role, but the thing that bothers me about the hate is that he's actually improved service over the past few years. Buses run more frequently, notification systems are being put in place, new subway cars and streetcars are on the way, Transit City (while admittedly not perfect) is well under way. Most the fuck-ups have been union-instigated, unexpected technical failures, suicides shutting the subway, middle-management doing stupid things on their own, etc. The fare increase was necessary, since the various levels of government aren't contributing. However, he gets all the blame for all the problems.
Personally, I don't think Giambrone should run for mayor. He's gonna get creamed. He needs to stay in his position of heading the TTC, he's not the problem, and all the dinosaur-minded nimrods who have been managing things there for 40 years need to be let go.