There is an underlying moral theme of doing the right thing vs doing the wrong (Royal) thing and covering this up to protect the Royal family throughout the series.
The complexities of relationships that a Royal Family holds with the public, politicians, the church, their staff and each other were well portrayed and mostly believable in each episode.
For the most part, the actors casted fit their roles quite well, with a few exceptions. The youngest Royal, Princess Isabel, age 17-18 in the series, played by Nathalie Lunghi, (age 22 in 2008), was made to look like a burnt-out '30-something' year old meth addict. Quite over-done in the makeup and over-acted scenes she had to do.
The same with several of the minor actors who played kitchen and wait and cleaning staff. Their scenes were so overacted they made themselves look like blubbering idiots who would NEVER be hired to work in a position requiring discipline, decorum and discretion such as working for a Royal Family. Very UN-Believable portrayals.
I blame this full on the Director, not the actors. They were just doing their jobs, as directed.
Overall, This was an 'easy to binge watch' 8 sessions series to escape from my little life's realities for a day and I learned a bit more about how and why things are done the way they are in the United Kingdom from medieval times throughout today.