It was rushed. The plot was the most interesting of the three in the series, but the story as it stands didn't take advantage of that. It left way too much out. Some of the interplay between Colin and Belinda was pretty good (like the interplay between Tamara and her husband), but there could definitely have been more of it. It had the makings of a great comedy of manners, with the main characters being perfect foils for each other, but it should have been at least twice as long.
As to all the naysaying about the ML, he spent the entire story saving her abysmally stupid, selfish, and ungrateful family from penury and having to live in a slum. Also, a landed Marquess is a definite catch, and the moneyed wuss boy they kept trying to marry her off to is the equivalent of catching a carp at a salmon derby.
Ending seemed rushed. They were the longest married couple and we were only allowed to see one child come from 3 weddings. She didn't even get pregnant like Pia. Also wishes to see the story of the ancestors but didnt