Other than the slapstick and sarcastic humour, I can't say I really cared for this movie. To me, it was much too formulaic and cheesy, loyally following other romantic comedies. The intersection of the four weddings and the funeral (the last wedding could also arguably be considered a funeral) was interesting and creative, but otherwise, the plot was bland.
I generally hated both protagonists because the majority of their relationship happens because they are cheating on their current partners. They never seem to question their actions or think "hey, maybe what I'm doing isn't right and I should wait until I'm unattached." Also, they both settle for people that they don't like, as if it's better to be in a relationship than single for even a second. There was no chemistry or even a reason for Carrie to be with her older husband (except maybe money) and I felt the same way with Charles and Duckface. Also, Carrie, unlike Charles, who is at least a somewhat interesting person, is as dull as dry toast and the scenes with her mostly consisted of her saying hi and smiling and talking in her "exotic" American accent. There were also a few painful scenes (like the generic trying on wedding dresses montage) where she desperately attempted to be interesting. I did however enjoy Charles' talent for getting into extremely awkward situations.
Sure, it's isn't Valentine's Day, but I would not call it a classic or even a good quality romantic comedy.