I have had my year 2000 2.7 for 2 years. It has 105,000 miles on the clock and leaves no drips of oil on the drive. I bought it with a complete Porsche service history which shows major work at 60,000 miles when the clutch was replaced. Otherwise it seems to have led a normal life with servicing and wear items replaced. I would call it a car which was used as a daily drive and well looked after, more than hidden away and taken out on sunny Sundays.
Like all cars they have their weak points. My opinion is that because of the type of car they are then the expensive failures get reported. We own a driving school and normal everyday cars have failures of very expensive parts but nobody shouts about it. A good example is the cables on Micra gear selectors breaking. Can you buy the cables, no, you have to buy the whole gear change assembly which has a parts cost of around £500 before fitting. Because they are an everyday car it goes unnoticed.
If you buy a car like a Boxster it is a technologically advanced higher performance car with lower sales volumes than everyday cars. A car like the MX5 sells in much higher volumes and has engines based on even higher volume units so problems are ironed out quicker than lower volume manufacturers.
They are fantastic cars. If you find a good example and look after it then you should thoroughly enjoy the car.