I'm an ex-local so I'll be blunt.
Get ready for:
* a high cost of living, especially housing, food, and gas. If he can get per diem it would be a lot better.
* island fever - limited professional arts/entertainment venues (Hawaiian entertainment is great, but not if you're used to the mainland one's), slow with the latest fashions (of course, nothing compares to NY, but things are very slow to get there), but there are many airplane companies that fly out of state so it's not like you're moving to Siberia lol
* yes, there is lots of diversity, but there is still racism (no matter how people say it's a "melting pot" )
* the island way of life is much slower than the mainland way of life (mainland being the continental US) - slower local drivers waving thank you is much nicer, but the traffic is still very bad
* they do a lot of things differently there, like real estate - fee simple versus leasehold whereas leasehold is you don't own the land under your home, but you pay a lease to use it
* corruption - it's common to hear about political corruption there
* "ice" or crystal meth is very popular there - my mom got robbed by a family friend and I believe when you get addicted you also turn to crime to feed your habit
* street racing is illegal there, but it has happened and unfortunately killed many innocent people
The best things:
diversity, no snow to slow you down and utilities are economical, he can go to work in Hawaiian print shirts, beaches, traveling to the different islands, yummy food, the aloha spirit, and the people are wonderful.
I love it there, I am part Hawaiian, and I love everything about Hawaii good or bad, but I gotta be real. Hope any of this helps.