In terms of the story, I was a little frustrated with the way that the four kids wandered around being all regal, and kept waiting for someone to snap and say, "never mind the posing; a slaughter's about to happen." The battle sequences paled in comparison to LotR, in that those films had a better understanding of strategy (use air support, and get rid of the artillery as soon as possible), and the duel was silly (helmets!). And the plot itself seemed to be, well, short.
On the other hand, performances were mostly good (particularly Susan, Lucy and Reepicheep; I spent ages trying to spot who was voicing the mouse, only to recognise Izzard towards the end), though I never worked out anybody's name. I particularly liked Lucy's dream sequence in the forest, and the constrast with the more naturalistic lighting immediately afterwards.
Some nicely dry dialogue too.