We really enjoyed our stay at Mike's place! It's a really unique spot a little ways off the beaten track. Our 3 year-old particularly enjoyed chasing the resident chickens and cracking open the coconuts that fell from the trees.
A few things to know:
*This place is great if you want something a little off the beaten track and away from the hordes of tourists (somewhat ironic, since if you're considering renting it you probably ARE a tourist). Ha'iku is definitely a small town; it's got a supermarket, a very good sushi restaurant, and a few little shops. Great if you're looking to get away and explore some interesting corners of the island, less good if you want a hotel / resort style experience.
*No A/C, but, as others have noted, you won't miss it. The only time of day when the house is really hot is in the early / mid-afternoon, when you'll probably be out doing other stuff anyway. The evenings are wonderful, with cool breezes and a view out to the clouds over the Pacific. Nice stargazing too, away from the city lights. It tends to be a little rainy in the morning, which we were fine with (a different perspective on the landscape).
*We do a lot of cooking--the kitchen has everything you need, but be sure to bring or pick up at the nearby store everything you need food-wise; there are no stray salt and pepper shakers or such.
*If you're staying with kids, there's a great playground (4th Division Park) a few miles up the road.
Overall, this was our favorite place we stayed on Maui (we stayed in 4 different locations). It feels remote, but is close enough to civilization to make you feel like you've really escaped. Highly recommended!