Why do the British critics dislike Death at a Funeral?

As an American, I had the opportunity to see Death at a Funeral in the cinema on the day it was released back in August. I saw it with several friends from Darcylicious. It was slow to start, but, by the middle, the entire audience was laughing hysterically. Yes, the plot was predictable, but the wonderful acting by the ensemble cast and the hilarious gags made it a fun 90 minutes. I wasn’t surprised when the critics seemed to universally love the movie. I wasn’t surprised when it opened up in other countries and it received the same audience reception and the same approval by the majority of critics. I point you to rotten tomatoes and metacritic, where you can read a summary of reviews by critics from around the world.
In Italy and Australia, this movie was the number one hit for several weeks. The budget for making this movie was only $10 million, but Boxofficemojo has reported that it has already made more than double that amount worldwide, even before the DVD has been released. It’s a success by any standard except for the standard of the British critics. Those British members of the forum who saw the film this week have also enjoyed the film very much, and can’t understand why the reviews in the UK have been so bad.
I am writing this post to let you, the readers, make up your own mind about this movie.