Hawaii has terrible public schools. It's the only state in the country with a single state run school district. Teachers are underpaid, schools are underfunded and deteriorating, and kids at all levels consistently score low on standardized test. A few years ago, the entire state run school district (k-12 + university) went on strike because the teachers pay was among the lowest in the country. The schools were shut down for 3 weeks. It's pretty bad.
There are a few private schools that are very good. Punahou (k-12) is probably the best and well known. It's the same school that Steve Case (AOL founder) and Barack Obama went too. But it's very expensive (I think $17k per year) and difficult to get into.
If you are really considering Hawaii and have children, you should really consider private schools if you can afford it.