Of late I have been reading several regency romances by Stephanie Laurens- the Cynster series and the Bastion Club. While both of these series are enjoyable, and have a balance between the romance side and the mystery that drives the story, I am starting to have issues with the historical accuracy.
I like history, but I would not have called myself an expert on early nineteenth century Britain. Unfortunately, neither is the author. There a few areas where I doubt whether the details are accurate, and there are some where I know the details are inaccurate. For example, in one book, set in the early 1830s, the main characters pay a visit to Harrods. Thankfully it is not described in much detail, but it is still interesting that they manage to visit a store that will not open for another few decades.
Once these details are spotted, they start to niggle and the whole construct of the story is shaken by distrust of these details. Was horse racing really like that in the 1820's? other sources indicate not. Was Vauxhall Gardens still a popular high society entertainment in the mid 1820's- sadly probably not. A lot of the areas are ideas about the regency (references to Prinny), ideas about London (that have no idea of the geography) and ideas about England that are more myth than reality.
The books are still readable, I just don't use them as any type of reference material.