Ooh its awful, there are two mr darcy's diaries so far as I know, one is terrible, its basically Pride and Prejudice copied, I think this is the Amanda grange book, and the other was a little surprising, with Georgina's elopement a little worse than what mr darcy wrote down and a bit dark, but otherwise, not exactly worth a buy.
Sequels are just so awful, published ones, I've yet to read a good one, fanfiction online is much better.=)