At about 200,000km the ABS control unit failed. This is apparently a common problem and it failed gracefully, leaving brakes fully functional, but with the ABS pump turned off.
The heater fan has a habit of squeaking a little. I have not yet managed to fix it as it is fairly difficult to get at (and spare time is so hard to find!).
The only other problems have been purely accidental damage - it is a little easy to scrape paint off under the front bumper when parking, as the front lip is a lot lower than you would think. I broke a side mirror at one stage, and replacements are a little pricey even with a bit of shopping around.
I have owned this car for well over a year now, and have clocked up a lot of miles. I can honestly say that this is the best car I have ever owned, and if I were to lose it, I would buy another Volvo 850 or V70 without hesitation.
The level of comfort is right up there with the best of the Europeans, and the whole car feels roomy and luxurious. The heating and air conditioning is the best I have ever encountered in any car, and the sound system (mine had the head unit replaced, but all speakers still original) is excellent.
On the road it is a delight to drive - responsive and well balanced, very quiet while cruising, and capable of a surprising turn of speed when you put your foot down. Visibility is excellent, and it handles well in snow or on unsealed roads. Even though mine is a non-Turbo model, I'm very pleased with its performance.
The engine is an inline 5 cylinder 20-valve NA, which is reliable, smooth and easy to service. It seems solid, and is well protected from the elements. It can be noisy when revving hard, but runs quietly at highway cruising or city driving.
The cabin is very comfortable even on long 5-hour highway journeys. The non-power front seats though can be very hard to adjust, though, with the tilt and height adjustment awkwardly positioned and likely to drop you with a thump if you lean the wrong way while pulling the lever. This is a minor problem though, considering how comfortable and luxurious the seats are. In the back, a fold out child booster seat is handy for a standby, but probably not for full time use. The back seat will take three large adults comfortably, with lap and sash belts, and full headrests for all three.
The cargo area is huge by anyone's standards. The back seats flip down perfectly flat in a few seconds to make enough room for a standard sized clothes dryer *in its box*, a six seater dining setting (with the legs removed from the table), or a wardrobe laid flat on its back. Even with the seats up, there is still enough room to put suitcases in lengthwise, on end. There is a good quality cargo barrier built into the back of the rear seats which can be used in both the upright or folded positions, too. There are cargo tie-downs and a roomy under floor compartment for a full size spare wheel. Even the front passenger seat folds flat, giving you enough room to take a kayak or surfboard if you happen to get stuck with one and not have your roof racks handy.
Safety is remarkable as well. You might notice the difference if you look at the engine mounts, the seat frames, the side door sills, or the chassis - but if you don't believe me just check out some crash tests of the 850 on YouTube or Google.
As for the looks - well, it's not to everyone's tastes, but it is smart and polite, and I like it.
If you do consider buying one, budget a bit extra to tint the windows; the large windows offer excellent visibility, but very little privacy and until you get them tinted you'll feel like you're on display to the world. Plus, it helps keep it comfortable in summer.
For the money you pay, you get an astoundingly good car that is capable, luxurious, reliable and a delight to own. It looks like it costs much, much more than it actually does.