Never heard of it before, but I chanced on it by accident on TV last night. Despite what many reviews say, I thought it was the funniest thing I've seen in ages - some fine satirical comedy insteady of the totally unfunny "alternative" comedy to which we're so often subjected these days (usually women in Edinburgh talking about their bodily functions that we'd rather not know about, followed by guffaws of forced laughter from a sycophantic audience). Refreshingly non-PC and irreverent, it brought back fond memories of the days when Spike Milligan, Monty Python, Mel Brooks and Co. could all put Hitler in some out-of-context situation and rely on plenty of laughs. Churchill - THY managed that many times but my favourite was Hitler having to bump start a car pushed by Eva Braun. Harry Enfield was brilliant as King George VI and Reeves and Mortimer (who I usually can't stand) had me laughing as the two effeminate lackeys.
To those waiting for something to be offended about, I say this isn't ultimately about poking fun at Churchill or the royal family, not even at Americans, but at Hollywood (which deserves all it gets).
Watch it with an open mind and look out for the many little asides that are easily missed.