I'm on Oahu havent tested on other islands
So I just tested it now in Mililani area and its MUCH improved this time. it was useless when i tried it 6 months ago, but today i needed to load it up with some data for a friend whos borrowing it. its pretty snappy now. So I guess YMMV with the device depending on what roaming agreements they have as well as what network the device connects to.