If you can afford to buy and run one, a Porsche is a fantastic tool. A comfy, stylish, head turning car with a great turn of performance. Other cars might offer a better performance (esp. per doller), but the 911 turbo is a proper supercar.
A couple of things to consider about them though:
Rumour has it that Germans themselves don't consider them a particulalry reliable vehicles. I'm inclinced to believe this, I've owned a moon mile 944 S2 in the past, and my fathers currently on his second 911. We both experienced problems problems with them, although mine was pretty old so I suppose it was to be expected. A couple of work colleagues have Boxters, one had an oil pipe come loose which siezed the engine with less than 1000 miles on the clock (replaced under warrenty of course!), the other had the plastic fins on the water pump disintegrate, and the car was back and forth to the dealers for weeks while they tried to flush the plastic out of the system which (they believe) was causing air locks resulting in overheating.
Secondly, be prepared for extortionate parts costs, particularly on a high end model like the turbo. I believe someone commented above that running costs are similar to a M3 - well I don't know much about BMW servicing but if thats true, remind me not to get an M3! Even seemingly innocent bits like the foglight plastic casing on a '89 C2 cost > £300, and from experience expect a main dealer servicing to start at £1k, despite what they say on the little cost board over the service counter!
Finally, be prepared for a lot of grief from people's attitude. This might not bother you, but was the reason I ultimately got rid of my S2. People (even "friends") see you pull up in a Porsche, and immediately their attitude changes. Its just envy - and its ridiculous, my Porker was worth a fraction of the cost much as most of their newer cars. Its something I havn't experienced in any other vehicle I've had, and I've owned much more expense machinery since.
If you can live with all these points, then get down the dealers today! The still 911 is my favourite looking car ever made, if I manage to win the lottery one day I'll own a 993 Turbo, like this one:
, but I have no idea how much they cost, it's probably a 90k Subaru. 
