Had them on for more than four years and did over 30.000 km / almost 20.000 miles with 5 mm tread still remaining. It would've been longer if I hadn't hit a kerb to avoid accident (not caused by me) destroying one tyre (collapsed sidewall). Their price has risen a lot, so since a complete set of Nokian Wetproof was available for basically the same price as a pair of Goodyears that was needed, all are going to be replaced.
In the beginning they were very quiet and absolutely safe in any conditions, offering excellent fuel economy. As time went by, and I really mean age, not mileage, they were gradually becoming noisier until tyre noise started to be noticeable. Still, there are much noisier tyres, e.g. my former Turanza ER300. It also seems that the compound, despite the "summer" wheel set was properly stored and cared about when "winter" set was on the car, has started to harden, which, sadly, leads to a few problems: small cracks start to appear, slight wheel wobble can be noticed and confidence in braking is dwindling (braking distances have started to increase a bit and the tyres are now in emergency situations slightly prone to wheel-locking). Also traction in colder central-European autumn conditions is far from what it was when they were new. This is, I think, a problem of "ECO-friendliness" and mileage hunting, but, sadly, potential danger too. Winter Continental TS 860s made in and used from the same year are not affected by that (at least not yet). Luckily, grip in the corners or aquaplaning resistance remained unaffected. Fuel economy also remained quite good.
Overall? They did a good job, Germans in Fulda who made them can be proud. More suitable for people who can wear their tyres in less than four years.