Despite all of these positive elements, there are some significant shortcomings. Caroline Bingley is much different from the woman presented in the first book. She was originally presented as a scheming, manipulative woman. She abandons the propriety that she cherished in the first book. The changes in her personality are dramatic and require an explanation that isn't fully supplied.
One one level The Other Mr. Darcy works well as a historical romance novel. It's a pleasant read and an enjoyable love story. But it's constrained by the original novel and the expectations that Austen's fans will bring to the book. It's a good effort but not great and pales in comparison to the original book. Then again, almost any sequel to Pride and Prejudice won't be able to match its charm.