I haven't read the book, but the more I learn about the Stoics (far beyond the simplistic modern definition of the word), the more I concur with you. I'm still a weekend Epicurean though :)
The interesting thing about stoicism is that most of the surviving texts (Letters from a Stoic, Meditations, The Handbook) are extremely readable. Letters from a Stoic particularly is fascinating. Making the connection between what Seneca talks about and issues in your own life is extremely rewarding.