Sailed this trip and had a marvelous time.
Unfortunately, no Hawaiian music, except that performed by the musicians on the Lido deck. I was surprised and disappointed by the lack of it.
There was a hula dancing class offered, and even though I have 2 left feet, I did participate, and had fun trying.
As a previous poster mentioned, there was a hula group brought onboard on Oahu, and they put on 2 performances in the Princess Theater. They were excellent - young performers, aged 7-17. They danced to authentic Hawaiian music, performed by 3 adult musicians. No grass skirts or coconut bras. They were dressed in beautiful traditional Hawaiian garb.
I don't know if they are brought aboard every cruise, but they were wonderful, and we were told they have won numerous international awards for their performances.