It’s fine for 4-5 hours - especially as a couple. Sure Polaris is better but most of the 777s United has on Hawaii routes are -200s with the non-Polaris 2-4-2 product which, while lie-flat, is embarrassingly bad. But again, as a couple that option is also passable for this duration of flight if you can get a pair of seats on the side. Either one beats the narrow body options from both carriers as well as anything Alaska/Southwest offers