Cheaper to run by a long shot in most cases (I changed my car to diesel of the same model and more than halved my fuel bill)
Sometimes cheaper to tax
But NOT as fun as a petrol car at all. If money wasn't an issue, I'd have petrol anyday.
Bear in mind if you're buying a car from new/nearly new and the diesel car costs more to buy then it's a false economy in most cases unless you're doing mega miles.
To all those who have said they are noisy/heavy etc. They really aren't any more. Driving a brand new diesel fiesta at the mo and it's SO quiet. (Better than any petrol car I know) and is really nice to drive. Plus manoeuvers are 'easier' to control
Thats mostly because the block has to be made of iron not aluminium
For the same power, diesels are faster in everyday conditions, ie without revving them up to 5000+ rpm. Less need for a downshift to overtake etc.
But a petrol is probably faster for the same power if you don't mind going to town on the revs, as there is less need to shift gear as you can go all the way to 6000 or so but in a diesel it's like 4500.