As I said, Palmer isn’t a complete disaster as Diana, I just wish she had more gravitas and physical presence for the part.
One of the weak spots in casting, unfortunately, is Palmer as Diana.
The show also left out a part of the character I really loved, which is the fact that her hair is always a static-filled mess because of the immense power that hums around her all the time, even though she refuses to try using it.
As a serious academic, and someone who rows on a regular basis for exercise, Diana was sold as being more mature in the book, as well as being a bit more substantial physically.