Does a U-shaped toothbrush clean as well as a regular electric brush?

There is no strong independent evidence that it does. It vibrates around the whole arch at once, but bristles cannot work along the gumline and between teeth the way a brush you move can. Most dentists still recommend a manual or oscillating brush plus flossing.

Is it safe for children?

It is marketed for adults and toddlers, but children should use it under supervision. The mouthpiece must fit their arch, and a child-sized soft brush is usually the safer default.

What does the 48,000 rpm vibration do?

It drives the mouthpiece to vibrate against the teeth for hands-free cleaning. That figure is the motor's claimed speed, not a measure of how much plaque it removes.

Does the UV light whiten teeth?

UV light in a consumer toothbrush has not been shown to whiten teeth. Stains respond to peroxide-based whiteners or professional treatment, not brief low-power UV exposure.