Pretty good. I felt it was a pity they felt obliged to hype up the battle. I suppose that's pretty inevitable though.

Big battles were needed in the Lord of the Rings, but in the Narnia stories the scale should be a lot smaller, more of a skirmish than a pitched battle with massive armies clashing. Squadrons of griffins dropping rocks on the enemy, and a napalm style phoenix are spectacular enough, but out of keeping. And it made it feel like a victory by the big battalions, Shock and Awe style, whereas it should be a victory against all the odds by the side that doesn't look like it has a hope. (The Lord of the Rings got that one right.)

Special effects are best when you don't even notice them happening, and accept them as real, until you start thinking about it afterwards, and realise they couldn't have been. Apart from the battles they managed that pretty well, I felt.