Let me preface this by saying that I love the books so much- they have been a joy to read, but I may have overexcited myself preparing for the film. There were a few things that I just felt were lacking, and others I felt were dealt with a heavy hand.
To start, I missed the friendship between Donna and Chris, and I felt there was so much else missed from the book. This should have been a series really, to allow you into the world and to fall in love with the characters as much as you do in the novels.
Obviously, Helen Mirren is brilliant, and so is Elizabeth, so thankfully, there was no disappointment there. However, in the novels, the characters are painted so clearly, and I felt that the three other leads were sidekicks to Elizabeth, which just isn't the case in the books. This is especially the case with Joyce- who only mentions Jerry at the end! It's Joanna who, rather obviously, shoves in a few 'since dad died's and gives us some semblance of a back story, but really, we don't get to see the Joyce that Richard Osmand created.
I also thought it was slightly too cheesy. Whilst the books are sweet as anything with wonderful heartfelt moments, the filmic versions of those felt eggy and forced. I don't think this was helped by the first 10 minutes of the film, which felt comically expositional and rushed to get us to know the characters. On that note, it was fractionally bizarre to see such huge actors as David Tennant and Richard E grant basically make cameo roles. I almost wish that they had cast less famous actors, as the roles were so minimal, I found myself actively watching their performances in these short scene parts, rather than enjoying the films and these rather important characters.
In all, I love the books, and they bring me a lot of comfort, so it felt a little disappointing to just 'enjoy' the film. I hope that any sequels they plan to make can add the weight to each character that the books do.