I think you mean Hawaiian Airlines (HA) now a part of Alaska Airlines (AS). There have been, and nothing has been announced about any, service changes with a few exceptions. On HA metal as they call it, which are still branded as HA flights it is exactly the same. Still on an Airbus, either single aisle A320 or widebody A330. Same sections, same service as it has been for years. Only minor change I know of is you now get free drinks in premium class on HA, which you did not before. You still get free meal only on HA, but still cannot preorder (maybe in 1st class).
AS flights also remain the same, on 737 Max planes. No free meal, but lots of small meal preorder options around $10. There may be (but I don't think so) some 787 widebodies out of SEA, but I don't fly out of there to HNL so am not sure.
For me I always get upgraded to premium, so can't comment on the value proposition. The extra legroom does make go to bathroom, etc a lot easier but if the A330, they have regular main seats that have only 2 on a side. I am not sure what/who flies from TX if that is where you are coming from. That's a longer flight than us on the west coast.
Flying there in about a week from west coast (on HA both ways as of now), so will update if real life experience differs, or if I hear anything different.