Yes, it's very impressive.. especially at sunrise. It's not something you could spend all day looking at, unless you take a trek down into the canyon... but it's definitely a wondrous thing to see. Meteor crater is not too far from there, either, and it's kinda cool, too.
For sheer beauty, I'd rather go to the Black Canyon of the Gunnison, in Colorado, but the magnitude of the Grand Canyon is awe inspiring.