I had one for about 18 months and 30k miles - it was faultless. It's a GM engine, EGR issues aren't too uncommon but they're more robust than some similar engines. The TTiD is a lot nicer to drive with a twin stage turbo but a bit more complexity to go with it.
Condition over mileage, mine was on 130k when I got rid of it and it was faultless. It actually popped up for sale again - a high speed 58 reg facelift, the guy had only done a few miles as it was on 135 and he was asking 3k. I'd have had that over a 50k mile older car to be honest!
The 9-5 is also worth a look, it's more equivalent to a mondeo in size. Just avoid the old 2.2 diesel and definitely avoid the 3.0 v6 diesel