There is quite a difference. It's much more user friendly. A few of the new things include clone source palette, nondestructive smart filters, improved brightness/contrast and vanishing point, refine edges feature, quick selection tool, improved black and white filter, adjustment and mask panels...there are so many. It's definitely worth the upgrade if you are going to take the time to learn about it. :)
Originally Posted by FJchickie
I don't know if this is the right place to ask, but... I have Photoshop CS and I'm thinking of upgrading. Is there a big difference from CS to CS4?