The second movie exaggerates the first trying for more laughs. Now, I could afford to lose a few pound myself, but hopefully you get the idea. In the second movie, the Colin Firth character seems to try to be even more nerdy than in the first movie. In the second movie, she almost always has low self-confidence. In the first movie, Bridget sometimes has low self-confidence. In the second movie he spends less time as a businessman and more time just seeming out for himself. In the first movie businessman Hugh Grant is mostly a businessman but is occasionally selfish and occasionally sexually selfish. Unfortunately this exaggeration tends to make things less funny and not funnier.
It is "Over the Top" as one in Britain might say. Instead it seems to fall back and simply exaggerate some of the elements of the first movie. The movie seems to lack the new elements that would make a sequel like this interesting. Hence instead of a witty fast paced fun movie where we laugh along with Bridget Jones, we have a slow moving non-funny movie that mostly seems to laugh at Bridget Jones and not with her. Yes, this film does have a similar story line and a similar cast, but the script and the direction fall far short of the original. In a sequel, often we are promised just part of that formula the basic story line and a similar cast. It worked well not only because of a good story line, great casting and great acting, but the script and direction made the film also both witty and fun. The original Bridget Jones Diary worked very well, at least in my opinion.
One person in our party watching this movie in fact called it "painful". Sometimes sequels to a very good movie do not work as well, and this one unfortunately is one that does not work as well as its original.