This is a great way to see the Northern Lights. You will have time to walk around, talk, get drinks and snacks and watch the lights from the top deck of a beautiful yacht. I haven't tried other lights tours but this appealed to me because of the ability to move around, go inside if it's cold, get snacks and drinks and see the Reykjavik skyline from the water. It was beautiful and the lights were amazing.
The only down side is that I don't think you will see the lights as brilliantly as you will out in the middle of nowhere. We had some city lights the whole trip and I think that dimmed the Northern Lights a bit. I didn't mind but it's a consideration if you really want to see bright green lights. The upsides were the drinks, freedom to move around and the ability to watch from a top deck or go inside if you're cold.
Overall, I highly recommend this tour.