I spent the summer living in Rome. Amazing city, full of life, great food, beautiful men-hating women, and a great public transit system. Housing prices are absolutely astronomical there, unfortunately.
Ok, maybe what I'm going to say is influenced by the fact that I live near Milan, and people from Northern Italy are usually thought to hate Southern Italy (and vice-versa), but this is my experience with public transit when I went to Rome on a school trip:
-Subways and buses always late and extremely over-crowded (also Milan subways are over-crowded, but Rome subways were... over-over-crowded 
)
BTW Stealth, I can only tell you to avoid Italy at all. Prices (not only housing prices, like fsphiladelphia said) are always astronomical. Public transit sucks (last friday there has been a public transport drivers strike: I was blocked at the uni for all the day ). Streets are always jammed. Crime rate is quite high. Justice is strange here ...
Well, there's truth to some of this, and I only lived in Italy for the summer, so I can't quite say with total accuracy like someone who lives there full-time. But what I will say is, that trains and busses weren't always late in Rome -- and the tram ran most hours of the day, until about 1 or 2 in the morning quite often. The pass cost only 30 euros for a month, and it gave full access to all trams and busses. Getting around Rome with no car was no problem, and we got around the entire city with ease, only rarely having to take taxis.
I will agree that trams, busses, and trains can be quite crowded. The streets are always jammed with both people and cars in Rome, so that is accurate, but to me, it was part of the appeal...I like cities with all kinds of stuff going on at all times with lots of people.
As for crime...I was under the impression that violent crime was pretty low in Rome. We were warned non-stop about pickpockets and possibly having our apartments broken into, but neither of these actually happened. I found that with the same amount of vigilance one would demonstrate in a typical American city, you were fine -- which simply means paying attention to your surroundings, carrying wallet in front pocket, not traveling areas you were unsure of at night alone, etc. That said, there were many nights I was wandering around the streets by myself or with only one other person or with only a female -- sometimes as late as 3, 4, etc., and I never encountered any problems. I'm also 6'2", 200lbs, and that's a bit larger than a the typical Roman male, so perhaps I was perceived as someone to not give a hard time.
I found that Rome was expensive in some areas, but not every area. I cooked very few meals there, so I was subjected to paying for almost all of my meals. It cost a bit after a summer, but no more than typical American east-coast cities, like Philadelphia, NYC, DC, etc.
My judgment may be skewed because as an American from the East Coast, I am used to expensive housing, copious pollution, overcrowding, bad traffic, substandard mass-transit (in my city, Philadelphia, anyhow), and the threat of serious crime, such as murder (again referencing Philadelphia).
I found that Rome was no worse than the East Coast in any of those categories, and quite a bit better in some of them, particularly transit, pollution (air, noise, etc.), and threat of serious/violent crime.
Final note of this rambling post -- I will admit that one time when I was riding the tram, it did derail, which was quite hilarious, and so that is a strike against one aspect of the transit system.
