The 2.5 engines are relatively solid. Issues are known with the injector seals (leads to oil in the fuel pump and requires tank and injector ring main fuel pumps and some other small bits to fix), driveshafts on 174bhp versions (only 1 side, dealer only part about 400 to fix from memory when my mates went) , flywheels as with all modern diesels. The cambelt/water pump are not issues with this engine.
Auto gearboces can be a problem and the last guy I knew who's went cost him £2300 to have repaired. They also use a lot more fuel than the manuals.
I had a 2.5 130bhp version which had done 130k when I sold it and apart from the injector problem it was solid for the year and 20k I owned it.
Any other concerns/requirements?