On mine (210hp, May '08, 15K miles) there is a bit of rattle for the first few hundred yards on a cold morning, after that it's very smooth and quiet. If anything I miss the noise my previous car (156 2.4JTD 10v) made. You either like it or you don't, but don't judge the engine on hearing one started from cold: you need to drive it for 20 minutes and *then* decide.
The reported problems are related to emissions control equipment (EGR and DPF) getting clogged up with soot. IMHO there are two things that make this likely to happen:
1. remaps, obviously this depends on quality and extent of the work done.
2. short urban journeys.
I reckon I will just about get away with it because it hasn't been remapped and, although I live in the middle of a city (Brighton/Hove), the daily commute is to the outskirts of a town 10 miles away with a fast stretch of dual carriage-way in between.
If most of your driving is in town you're very likely to hit EGR/DPF issues.