He should find out if they treat one eye and see how it goes. If they do both eyes and get it wrong you are in big trouble. I would not have this at all but there may be others who have had a good experience.
What's the success rate like? How long will the treatment improve his vision for. What happens if things go wrong how long has the firm been in business, how many people have they treated, who does the surgery, where did they train and what are their qualifications, how much experience do they have (and "lots" is not an acceptable answer)
Another question to ask is how good the vision will be after laser treatment compared to what he can get at present with his glasses/contact lenses. My other half considered laser treatment, but then was told by his optician that in fact he was able to get 20:20 vision with contacts, but only 10:10 with laser treatment. In the end he decided to stick with his contacts.