I loved both of the films I did however grow up with the BBC versions (every Sunday afternoon for the next half hour episode!!) and so naturally did a straight comparison:

LWW:
Good scenes:
- I actually liked the fly in the window as Lucy walks to the wardrobe the first time - was very like the book.
- Loved Aslan's death scene - very moving.
- Thought Tilda's WW was convincing and liked Skander's take on Edmund.
- Loved the battle scenes and Aslan really going for the WW rather than just growling and her dying whilst falling off a cliff (remember - I'm comparing!)

Worst scenes:
- The fact that Lucy walks into Narnia for the first time and is NOT cold!!!!!! I have to give the BBC props for actually taking the kids somewhere cold and making them feel it! Really annoyed me that.
- The kids running to the witch's palace so quickly after realising Edmund's death.
- The fact that Narnia is about the same size as my local park.
- Hate to say it but the American accents, wouldn't normally bother me but the humans in Narnia came from London or Spain, just felt wrong to have American accents. Minor point though

And much harder to do since they changed the story so much...
Prince Caspian:
Good points:
- The scene at Miraz's palace. Completely new but I liked the failure of the army to do it in their own strength so to speak.
- Loved Lucy finding Aslan. Loved Lucy's lines to be honest.
- The white witch being called up. Again completely new but the point of the WW was that she did deceive and could convince you to fall for her, remember she was meant to absolutely spellbinding. Loved Edmund's destroying of her.

Worst scenes:
- The very beginning with Susan being a snob - didn't take to Susan at all in this film.
- Ben Barnes' accent.
- The kiss at the end - but that probably has more to do with the awful crush I have on Ben Barnes.

There you go!