How long does the Shark Freestyle Pro run on a charge?

Shark rates it at up to 20 minutes, and that figure is for the lower speed. Expect less on the higher setting, and less again as the battery ages.

Does it work on both carpet and hard floor?

Yes. It has two speed settings, one tuned for carpets and one for hard floors. There is no automatic floor detection, so you switch speeds yourself.

Is it good for stairs?

It is light enough to carry, but it is a full upright with no handheld mode or tools. Stairs and upholstery are awkward, so a stick vacuum with a detachable handheld unit suits them better.

The dust cup is removable and empties with one touch over a bin. It is small, so plan to empty it after most sessions.

How does it compare with Shark's larger cordless uprights?

Bigger Shark cordless uprights offer longer runtime, larger dust cups and more tools. The Freestyle Pro gives up those for lower weight and simpler handling, which suits quick daily passes rather than deep cleans.