They give an increase in speed like say Ninja boots in FF XI. Its pretty fast. I would say its about a 35% speed boost and it last for 15 mins a day but you can only use it once per 24 hours.
Is there a visible timer anywhere that shows cooldown period/when the shoes can be used again? Am I missing something, because I can't find one - though me getting familiar with XIV and not looking in the right place is definitely a possibility.