Keeping in mind that the car was 10 years old when I bought it, in the 10 years since, I've replaced:
Alternator bushing (just the bushing, not the entire alternator).
Additionally, I had to replace a couple of minor hoses and sensors, but they were so inexpensive they're hardly worth mentioning.
In all I've been averaging about 1 in-garage repair a year. In all I've probably spent around 2000 in repairs over the past 10 years not counting the occasional brakes, tires, and batteries.
The only issue I would say is problematic would be the electrical system and/or wiring. I have to keep a steady supply of spare tail lamps in my glove compartment, due to a short in the wiring that my mechanic says is a common problem with Volvos. This can of course be fixed, but the labor alone required to track down the short would be astronomical compared to the 1 or 2 bucks I spend a month on replacement lamps.
All in all, my Volvo's been a wonderful car. Faithful as an old dog and sturdy as a tank (I know because she's had a few close calls and still runs like a champ).
Volvos have a reputation for running half a million miles or more. I'm at 200,000 miles and still running strong.
As far as style is concerned, the older Volvos are timeless classics. Not everyone enjoys the "brick", but what's great about them is that they're immediately recognizable and resemble nothing else on the road. Once Ford took over of course this all changed. The newer Volvos are often confused with Toyotas, Mazdas, and Suzukis.
Parts for repairs are generally slightly above average in cost, but well worth the investment. With even the minimum amount of maintenance, this car will run forever.
Seats 4 average sized adults comfortably, although I've had male passengers complain about head room.
Drives and handles like a European car (If you've driven European cars before, you'll know what I mean. They feel completely different from American cars or Asian imports).
Best to find a mechanic who specializes in Volvos. Most other well intentioned mechanics will simply waste your time and money trying to isolate a problem that a seasoned Volvo mechanic can diagnose in seconds.
Mild vibration common among Volvos.
I've had my Volvo 10 years, and would gladly keep it 10 more if it didn't look so rough. The leather seats have cracked, the paint's fading, and I have a few dings and dents from a couple of close calls. I'm in the process of searching for another car now, and I plan on it being another newer model Volvo.