A good car overall. It's clearly not cheap to run, as it had a higher sale price when new than a lot of similar used cars for the same money. BMW didn't turn much of a profit on each one.
Price of servicing using specialists is very cheap. However anything over and above this is pricey, eg £700 for a new clutch. A new water pump, tensioner, cam belt and coolant change is £600-900. This is a 60000/6yrs item. Tyres are pricey as well at £260 for 2 good tyres.
All that makes it sound like a bad car to avoid; it's not, it's a good car. A lot of the pricey stuff can be used in the haggling, so you can negate the big ticket items off the price.
Fuel wise not too bad; 30 mpg on a long run. Low 20's round town. The diesel is very good at 550-600 per tank.
Very nice interior, no squeaks or rattles, and it has a nice layout. Mine has radio/CD controls on the wheel, which are nice and easy to use.
Very little glovebox space, as the 6 disc is in there. To make up for that, there is a space under the drivers armrest. Plus the door pockets are big and you can get plenty in.
Leather seats come as standard. Good enough, not too many problems, took me a while to get comfy, but that might have been me.
Speed wise it's easy to overtake, not as good I've noticed than a lot of brand new diesels. But then they are brand new and the KV6 engine is around over 15 years old, so it's no real surprise. The difference isn't massive; they aren't going to fly away from you, but equally they will slowly pull away from you. On the plus side, the exhaust note is great, and the engine loves being revved hard. If you want to be blasting all sorts of cars away, then this isn't the car for you. Buy the V8 instead!
Handling wise, a bit above average, not pin sharp like a lot of Fords, but this car does weigh 1.5 tons, but it's fine unless you have a thing for track days.
No big second hand car is cheap to run. Get a duff one and you can be splashing out cash all over the place, this is no different to £3k BMWs/Mercs. But they are a nice car to drive; you can just waft about.