I was reluctant to purchase this at first but at 29.99 for five tours on the Big Island, probably one of the best bargains you'll find in Hawaii. This guide is really easy to use and Shaka was incredibly informative. Love how it integrates with GPS on your phone so it knows exactly when to start playing. The guide keeps the drive interesting by providing history,details, step by step directions and recommended places to stop. By the second tour, the kids were also into it and demanded we play the guide while driving each time. It is well prepared and incredibly helpful. As they will tell you, its very important to download the tours in advance, since cell signal can be spotty on MANY parts of the island. Once downloaded and you keep the phone plugged in, it works quite well. The musical interludes were awesome too!
My only comment would be to add some more restaurant options and info on possible street side stops, just to add more info for the tours.