I used to work for them and they're pretty good. I stopped because I preferred to work in a salon. The commission is generous. Their clientele includes high profile/ VIP clients, well known bloggers etc and they do events like product launches for companies and so on. If your son has the opportunity with them, I'd say go for it. You meet a lot of nice people, he could get to work at BeautyCon. They also promote their agents on their social media.
I would say prepare for ALOT of travel and rushing. Sometimes you could get two bookings with an hour to travel across London between them.
Hth