There's a history of Mars missions going wrong (remember the failure that was caused by the imperial/metric confusion?). So I really hope it all goes well this time. I'd love to see some pictures live from Mars on Christmas Day.
BTW, on the news it said that Prof Pennington, the guy in charge, was not allowed near the equipment as it was constructed because of his bushy sideburns. The stuff has to be prepared in sterile conditions, and no-one with facial hair was allowed to contaminate it. The Professor refused to part with his beloved sideburns, and so had to supervise from a distance. Long live British eccentrics *g*