Its does make you think about these "economical" derv engine cars, they do better mpg, but if you DIY service an Omega you save a fortune in service and parts costs, which probably makes them overall cheaper to run. Just not at the pump!
For the first 6 months I was thinking how reliable and economical it was, only had an oil change done when I first got it (even though one wasn't due, but peace of mind and all that), and had to get steering gaitors replaced for the MOT and since then nothing. Was returning close to 50mpg too, so I thought I was quids in. It's only now I'm hearing that thing like the DMF are common failures on the Mondeo.
As someone has already mentioned, I suppose every car has it's weaknesses, but it seems like I always find them! 
Vectra's have similar issues with DMF too, not sure on later Insignia's

BMW's have swirl flaps, now causing issues on bikes. So all cars have issues, guess secret is understanding them and taking preventive measures.
Take motherT's estate, needs two new rear shocks, just age, they have failed (think they are original!) Retail price for self levelling shocks is £120+vat each, so say £288 for shocks + fitting. 2 hours labour I think is fair, so £80 rate about average? Not far off a £450 bill if taken to a garage.
But I'm getting them on trade & fitting myself, end cost around £180.
£270 buys a lot of fuel! Going to take many 1,000's miles to recoup that with an economical derv VS thirsty V6