This was by far the best thing I did during my whole trip to Hawaii. I was most excited about the sunset on the summit. It did not disappoint - it was the most beautiful sunset I have ever seen. However, I also thoroughly enjoyed the stargazing part of the tour. My tour guide was Hunter. Hunter was clearly very passionate and knowledgeable about astronomy (and about Mauna Kea in general), and provided a wealth of knowledge during the whole tour.
Overall, the tour was also very well organized and ran smoothly. It was a very enjoyable experience and I highly recommend you book this tour.