I'd been wanting to see this movie for the longest time. Finally saw it last month and was very disappointed. I enjoyed about the last 45 minutes ... but up to that point it was very dull.
Now that I'm over the big letdown, I'll probably watch it again to see if I like it any better. If I don't, I won't be watching the sequel.
@Wahoogaz I think a lot of the enjoyment factor comes from being a big fan of Agatha Christie's mysteries.