I have one of the new Unibody MacBooks and it's as well built, sturdy and polished as any laptop I've ever seen. Particularly what strikes me is it's strength and structural rigidity. You can hold it by the corner and there is no flex whatsoever. The same cannot be said for previous gen MacBook Pro's and Powerbook's etc.

As another poster mentioned though, the white MacBook is a replacement for the iBook and built to a lower quality therefore.