Found this on the Road to Hana drive and was not sure exactly what it was, so we turned in and were pleasantly surprised! After initially considering turning around at the $10/person fee for the garden, we bit the bullet (like we haven't already spent tons in Hawaii already!) and entered.
After parking, we hiked the trails within the grounds and were amazed at the beauty of the foliage and views the Garden had to offer. We saw waterfalls (with people swimming under them) as well as ocean views that were awesome, but the vegetation and colors are what will really keep your camera busy.
The "bird show" at the end of the tour is where a bird trainer/world renowned photographer grabs his exotic birds and places them on your shoulders, arms head and hands for a pic. He then offers to take his professional pictures with your camera for $20 - we passed on the offer and it seemed his whole attitude changed, asked us to stop taking pictures and video… I understand this may be how he makes his living, but he also needs to understand not everyone needs to say yes. The birds are pretty but if you want to avoid the hard sale, keep driving.
Overall, the views and colors are worth the price - you can spend a lot of time in here so be aware of your agenda on the road to Hana, but it is worth it. Your reward will be great views and awesome pictures, even if you are not a world renowned photographer.