Kara alone has smashed many raid groups accustomed to the more forgiving 40-man game, to say nothing of the road to Serpentshrine Cavern and The Black Temple. The Collector’s Edition is worth having, particularly if you’re a fan. There’s an excellent coffee table book that shows the evolution of the art & design of The Burning Crusade.
https://www.amazon.com/World-Warcraft-Burning-Collectors-mac-pc/dp/B000JGJ6K0