Whether you've watched the TV series or not, this book is worth a read, and in fact this is definitely one of the situations where I'd advocate for doing both. Even though the author and the scriptwriter are one and the same, there are areas where the book was able to capture the thoughts and emotions of the characters better than what was produced onscreen, and surprisingly also vice versa - the actors sometimes gave more depth and conveyed more moving portrayals of characters than they came across in the book.
i don't often like sequels, but this one - this one is worth it. It's a wonderful combination of the most romantic elements of Asian ideals, with just a hint of the modern creeping in with the uncharacteristic independence and career focus of the female leads. Mmmm ... a somewhat apt yet unappealing comparison would be ... Braveheart meets Game of Thrones?