I actually agree to a certain extent when it comes to smaller children. I see a couple of really little kids in the cinema squirm when the Werewolf change happened, that is pretty scary for little ones. I would say it's ok for 8 and above though, to say it's not is underestimating kids in my opinion. They can take alot more than people realise.
It's PG in the UK and I agree with that. I think PG-13 and 15 is way too high.
What is GOF gonna be and OOTP - an 18??