I had an 05 plate one! Graet car in my opinion! Consistantly got near 50mpg and performance is great. Sagging rear bumper is an issue on all cars because ford never fitted the foam bumper supports that were fitted to the zetec s.
Well specced cars as standard, all mk3 mondeos seem to suffer from rear wheel bearing failure at some point, I had a few qoutes for my wife's zetec estate, Ford charge £205 each, SKF (who supply Ford) want about £100, I got them off ebay for £37 each, easy job to do as it's the whole hub you replace.
I don't think the 2.2tdci engine suffers from as many problems as the 2.0 lump and they respond well to tuning. Most are putting out more than Ford's quoted power figure of 155ps as standard anyway, a chip and larger intercooler, can see 190bhp easy.