In this story, the good warriors of Prydain see that the Black Cauldron, which makes deathless warriors, but must be captured and destroyed if they are to have any chance at all. Knowing the plan ahead of time, you know that the plan will go wrong, and so it does.
Although the book still contains a few Tolkienisms, such as a black gate, many improbable meetings, and even more improbable battles, the story holds together quiet well, for the focus of the story is not on the battles, but the decisions that get our characters from point A to point B. While the first book promised a Celtic style story, but only dressed the story up in Celtic clothes, this book delivers to us a Celtic story with a wonderfully mythic feel. Yet, being a more modern story, we still have to hear about making camp and sitting guard.
Our hero Taran now has more personality, and a temper that gets him into trouble. He also has an internal intrepidness that also gets him into trouble, but for all the right reasons. Eilonwyn still has her attitude, but she is nowhere near as inscrutable, off the wall, or cutting as she was in the first book. She's trying her best to be a real character but not quite there yet. Meanwhile, our trope characters (the bard, Gurgi, Doli) continue on in their trope-centric ways, being exactly what their stereotypes make them, sometimes wonderfully so, but sometimes annoyingly so.
My inner thirteen year old would have loved it.