Overall, Sanditon was an entertaining drama loosely based off of Jane Austen's unfinished novel. It is certainly adapted for modern audiences, as many of the plot lines would never have been allowed to print in her time (Arthur's story in particular).
Charlotte Heywood may be the main character, but she was not the strongest performance. I felt that most of the other storylines were far more interesting than Charlotte's endless stream of 'will they, won't they' plots. I understand that the departure of Theo James meant that her storyline would need to pivot, but Alexander did not have nearly the same chemistry with Charlotte as Sidney did. She was still an interesting character, but her story bounced all over the place with no emotional payout until the final episode.
That being said, I found the Esther/Babington, Lady Denham, Arthur Parker/Duke Harry, and Georgiana Lambe stories very compelling. I wish that Clara was given more of a tidy ending, or at least a little more background (she had hinted at a tumultuous childhood) before she shipped off. I would have also loved to see Esther and Babington with little George instead of getting the Edward 'redemption-ish' plotline (though I did appreciate the Fuchs/Ms. Hankins romance that came from it).
I also could've done without the whole Alison Heywood, redcoat, Colonel Lennox storyline. I felt Alison's romance(s) were shoehorned in without much thought, and the actress for Alison gave one of the weaker performances in the show.
There were some plot holes, but Sanditon is a fun drama to be sure, even if it falls slightly short of our favorite Jane Austen adaptations.