Decent to good watch, probably won't watch again, but can recommend.
There is a whole range of movies that "have to be" bar bets. Someone bet Vanessa Hudgens she couldn't do a Lindsey Lohan "Freaky Friday" or an Anne Hatheway "Princess Diaries" and someone she knew had a Christmas season slot coming up so they made this.
While everyone else in the cast is fine, the only other actor really worth mentioning is Mia Lloyd, but I'm sure it is easy for a competent, spunky kid to play a competent, spunky kid.
The storyline is simple enough, if not powered by plot serendipity. It's fairly amusing, including the bad British accents, but it lacks impact.