During the evening at Pemberley scene (just before Caroline's remark about Wickham), Georgiana sounds like she's practicing her piece or playing it for the first time, not performing it for an audience, and I've said previously that I find Elizabeth's performance a little too good (though not irritatingly so). I think it should be the other way around - I would expect Georgiana's performance to be better than Elizabeth's, despite the difference in their ages. After all, Georgiana loves music so much that she practices for hours every day, while music is not Elizabeth's specialty (though she obviously plays).
When Darcy arrives at the inn just after Elizabeth has finished Jane's letter, I must say I find their dialogue a bit repetitive, even though it's taken from the novel. Colin Firth keeps saying "You are not well", while Jennifer Ehle keeps repeating "No, I am well". Also, JE doesn't look unwell at all, just unhappy and with tears in her eyes (though I realize that paleness, shaky knees and feeling faint are very hard for an actress to convey!).
On the other hand, I love the little scene during the dramatization of Jane's letter when Jane's voice says "To Kitty, however it does not seem so wholly unexpected", and the camera shows us Kitty's face, and then her father's with one raised eyebrow. Their expressions just say it all!