When I first got the car, it suffered from a spongy brake pedal. The standard fixes didn't seem to work, and the independent service place tried a bunch of (expensive) things. It ended up being a combination of the brake pedal height adjustment and rear rotors that needed replacing. The rotors seem to wear fairly fast on mine, and for some reason, the rear brakes wear out before the fronts.
The interior electrics have been a bit unreliable, with 2 power window switches and 2 seat adjustment switches breaking.
My rear anti-sway bar brackets ripped out from the body and had to be welded back in.
The fuel pump also died this year, which is a bit pricier than most.
With all the above, you would think I'd be ready to ditch this baby, but you'd be wrong! The engine growls like no other (my family always knows when I'm coming or going). The styling is very unique. There just isn't anything like it.
I recently considered replacing this with a new 350Z. The Z is faster, handles better and stops quicker. It just didn't have that raw emotion of driving a semi-race car. I'm enhancing my 911 instead.
One note to anyone considering a 911, don't skimp on tires. I had all season Michelin radials on the car and thought it handled pretty well. I switched over to Michelin "summer" tires, and the change was unbelievable.
As others have said, maintenance is key. Much of the car is actually pretty easy to work on yourself, in fact I ended up doing much of the brake work myself. It still costs more than most cars, but that's the price you pay for performance.
And it does perform. Below 3500 RPM, you can putt around town comfortably. Wind it up over that, jamb on the brakes and dive into a corner, and you're an instant racer! After 6 years I'm still not tired of it.
Every article says to get the most recent Porsche you can afford. Newer models will get you air conditioning that actually cools you down, ABS brakes and power steering. However, I'm not sure it will get you any more fun or reliability.