Good and bad things from my perspective, just picking a few things that stand out:
Good
- I actually really like the Telmarine characterisations. Glozelle and Sopespian, to my mind, got rather too little book-time. The fact that the Telmarines weren't just a single, externalised threat led by Miraz made them a much more interesting enemy.
- Trumpkin. Trumpkin is one of my favourite characters in the whole series, because I see vastly more of myself in him than in other characters. Which is interesting, since of the three (Nik, Tkin, and Trufflehunter) Lewis clearly wants us to favour the latter. Trumpkin, though, is almost unique in the series in that despite his disbelief he is not strawmanned as acting with pure depravity/self-interest. He acts out of loyalty to Caspian and duty to Narnia as his primary motivations, which makes him quite an interesting figure.
- Reepicheep being Reepicheep. 'nuff said.