Does it massage the feet too?

The wraps are sized for feet up to 14 inches as well as calves and thighs, so you can use it on the feet, though the compression is air-based rather than roller-based.

How hot does the heat get?

There are three heat levels, with the highest at 140 °F. That is warm rather than deep heat, so it suits gentle soothing.

Will it fit large legs?

Comfier lists thigh fit up to 27 inches, calves up to 19 inches and feet up to 14 inches. Larger legs may find the straps tight or slipping.

Is it a shiatsu roller massager?

No. The shiatsu mode is an air-compression pattern, not rotating rollers, so expect a squeeze-and-release feel.

Can I use it while walking around?

It is a plug-in wrap device, so you stay seated while it runs. The cords and bulk make moving around impractical.

Is it worth it over a cheaper foot massager?

It covers calves, thighs and feet with heat, which basic foot massagers do not. If you mainly want foot rollers, a dedicated foot massager may suit you better.