Not going to pretend I'm from Hawaii or anything and say that this place is authentic. However, after visiting Hawaii and eating plenty of the local food, I can say that it comes somewhat close.
I love me some hamburger steak so that's what I ordered. There wasn't enough gravy but the taste, rice and mac salad made up for that. I enjoyed it very much.
My family and I shared the large saimin noodle. The soup wasn't very tasty (I think I'm just used to ramen broth) but everything in it was good. It just wasn't like "OMG THIS IS DELICIOUS." We also had some korean chicken, which was pretty good. I would have preferred it to be crispy all over just not on one side though :p
Overall, it was a great meal and the portions are a good size. I think it's a tad pricy, but it IS in a casino (California Hotel and Casino). The line is long, so expect to wait. Also, seating is limited. I would come back if I had some extra time during my next Vegas trip and was seeking some comfort food.