I've got one and had one for two years, it is definately (IMO) the best car for the money that you could own hands down, it pains me that the miles are getting high and it's getting on a bit becuase I will have to buy something not nearly as well put together and fast, anyway enough of the sob story, what is it like....

-Well for starters their cheap to buy, so don't opt for a pre-facelift car becuse you'll pick up the later one for the same or similar money.
-Mine averages 17.8 mpg but thats mostly town diving.
-Brakes are not the best, get uprated pads as minimum and the discs are prone to warping becuase its a heavy car.
-Vanos issues are a load of old wifes tales, it sounds like a bag of spanners when you start it up, that should last for 3 seconds at most then it'll be smooth, this is perfectly normal, i've even had non BMW mechanics freak out at the noise it makes when you start it.
-Cheaper to service than an E46 M3
-Don't just buy on mileage, i.e and 85k mile car might need tyres/brakes etc done to it, whilst a 100k car has had all that done already.
-Problems.... err I've had none, cars at 120k miles now and clutch is slipping but i do drive it hard, other than that it's had tyres all round, front brakes and two sets of pads and a track control arm so nothing to shout about really.
-Top tip, bits arent that cheap but DON'T buy pattern parts, I have only done this once with a set of rear drop links and they lasted 2 months and broke, thesrs alot of cheap shite out there and it's a big heavy car, so only use BMW OEM bits.
-They use oil, it is VERY rare to find one that doesn't, the also ONLY run on castrol TWS 10/60 FOR M SERIES ENGINES (it MUST say that on the bottle), its about 45 quid for 4 litres you can get it off ebay/opie oils etc, or BMW if youre feeling flush.
-Check the rear diff for play, if you can't jack the car up, just lift the clutch slightly when you pull away and see if there is a noticeable delay in it taking up drive, oh and the rear diff seals are very shit and are prone to leaks.
-If you drive it from cold the gearchange can feel notchy, this is a characteristic of the box and it will be smoother once warmer, again nothing too bad but some people moan about it on forums, even old dudes that have had them from new complained about it.
-Headlights (in facelift cars) break on the inside, the adjusters are made of plastic and become brittle and snap, easy and cheap fix if you have a heat gun. if you open the bonnet and wiggle the connector that goes into the light and it moves excessively you know the inside of the light is no longer connected to the adjuster.

Other than that it's an ace car!