I was looking forward to Jonathan Creek, but was rather disappointed, with the distinct lack of realism. Where were the police? First a girl goes missing and nobody seems particularly bothered and the police aren't called. And then when a water tank full of bodies is discovered, still no police. When in reality they would have been tearing the place apart. I also thought the bath was pretty obvious, under it would be one of the first places I would look. IMOP definitely lacking the quality of the earlier series.
I am a massive fan of Jonathan Creek and was really looking forward to it. I agree about the lack of realism concerning the police and the rather simple explanation of the "Nightmare Room" but I still enjoyed it, and as Condom says in comparison with most of the other Christmas offerings it was still very watchable.