The BBC iPlayer draws criticism from many corners and the decision to launch it on Christmas Day is not going to do much to deflect the criticism it has received so far. PC Pro has an article with the headline 'Is iPlayer heading for a Christmas nightmare?'.
Christmas Day is probably not the best day to launch a new piece of software, particularly one that could have an impact on the pattern of broadband usage across many broadband providers. The iPlayer has been available for some months but in the guise of a Beta release, so in terms of the risk of the software having problems this is probably very slight, unless there is a large pool of people who are not using it yet because of the beta tag.