Even the most casual conversation in Hawaii will reveal whether you have truly embraced local values by how you pronounce Hawaiian words. Get them right, and you send a clear signal that you're "one of us". Pronounce Hawaiian words the way most mainland folks do, and you make it loud and clear that you've not really embraced our way of life and it's just a matter of time before you will leave.
If you truly want to live in Hawaii for the long term and become an active member of the community, correctly pronouncing Hawaiian words is an absolute must.