Complex sentence: This book shows Hornblower's contrary character more strongly than many preceding books in the series--he is unable to be happy or self-satisfied in spite of accomplishments highly valued by others, including both professional and personal success.
Split into simpler sentences: This book shows Hornblower's contrary character more strongly than many preceding books in the series. In particular, he is shown to be unable to be happy or self-satisfied in spite of accomplishments highly valued by others, including both professional and personal success.