PS CS2 vs PS CS3

Is there much difference between PS CS2 and CS3? Which one do you all prefer? Is CS3 just a newer version of CS2 or is it better/just as good? And the animation program that comes with CS3 is it like imageready. I've only just learnt how to use imageready properly and was wondering if the animation part pf cs3 was just as good.
Hope you all can help. Thanks.