I can't comment on the U of G, but I travel to Guam once or twice a year for work and love it there. I have terrific clients I deal with and have made several personal friends on island.
As HkCaGu stated, the cost of everything is higher than the CONUS and will be extremely high compared to OK. Gasoline is $1 per gallon higher than I pay in So. Cal. and that's usually $.40-$.60 higher than other states. Since Guam is tropical, running the A/C is a 24/365 proposition and electricity there is outrageous.
Not only is the airfare expensive between Guam and the CONUS, the travel time to and from Guam takes anywhere from 18-25 hours. It's not like you can jump in the car and be at granny's in a couple of hours for Thanksgiving dinner.
What about jobs? Most jobs on Guam are in the service industry and pay federal minimum wage.
On a positive note the people there are wonderful and the water is clear and warm.