A comfortable car is comfortable every time you drive it. A fast car is fast when weather conditions, road traffic conditions, road surface conditions, speed cameras, passengers and petrol prices permit, which is almost never. People are looking to buy smaller, slower, quieter, more economical cars these days, and Autocar needs to realise this.
The C5 looks at least £2,000 cheaper than any equivalent Mondeo (I'm guessing that the ubiquitous Ford was the sharper-driving alternative to which the author was alluding in his article), and is predicted to hold its value better too. While Citroen dealers get a roasting in satisfaction surveys, what they sell is proven more reliable than Ford or any German rival, and cheaper to repair should things go wrong. Check any claims-based survey.
Aside from the Mundano being larger and subjectively "much better" in terms of hustle-ability, it lacks Hydractive - the air suspension system which puts every Citroen estate at the top of its class for load lugging. Hydractive adjusts itself to negate the effects of what you have in the back, passengers included, and delivers a supple ride quality not far removed from luxury cars costing three times as much. Luxury cars, I might note, that are not for hustling.
Perhaps when Autocar write up a full review, they'll look at it from a buyer's point of view?