This was a real mess for me on Saturday. Had an outbound on Mokulele HNL-OGG. No phone call or email whatsoever. Showed up to check-in at a loooooooong line at the counter. Didn't see my flight number on the screen, and after inquiring, found out I was now on a flight about an hour and a half later than originally scheduled. Very frustrating to say the least. For my return OGG-HNL today...got a phone call a couple days ago advising me of the change and offering either a refund or new flight options. No problem there.
The one thing that really made me angry for the HNL-OGG leg was that I immediately asked for a refund as I was going to walk over to Hawaiian and book a walk-up fare. I was told by the Go! (Mesa) employee that they weren't able to do that at the counter and that I'd have to call the reservations department. Lame.
That said...the Go! flights weren't terrible. 20 minutes in a CR2 isn't the best way to spend 20 minutes...but perfectly acceptable. Drinks are CHEAP. And they have "happy hour" where beers are $1.50 (everything is $1 off as far as I could tell).