Earlier quoted context omitted.
The usability was very good. The appearance was goofy and Fisher-Price-like. The two things are mostly orthogonal.
I wouldn't say orthogonal. Making something inviting, approachable and feel like a safe place to experiment/explore for a novice is a critical and overlooked part of usability. The childlike choices of "bright primary colours" and "no sharp edges" is one way to attempt that. It's what the general public needs that us nerds can least relate to.
The best-looking Windows UI, IMO, was Vista.