First off, the one bad review was from someone who asked around if there was lava flowing in the Volcanoes National Park... this tour is not in the park... his loss for not taking this tour.
What we did:
My father and I took this tour on the 2nd week of December 2012 and it was one of the most memorable experiences I've ever had. We met up around 3:30AM and hiked to the lava fields. We got to the lava while it was still dark, so we were able to take really cool photos at night and also of the lava and us standing in front of it when it got light out. Chris was so much fun to hang out with. He lets you play with the lava, poke it with sticks (in my case fling it too) but also makes sure that you are safe. We also did lava surfing (standing on a cooled piece of lava riding on top of molten flowing lava), which lasts about 1-2 seconds if you can bear the heat.
Chris is a really laid back guy and knows a lot about Lava, the island and its history. He's also very opinionated about current events, politics and conspiracy theories.
About the Hike:
The hike is about 3 miles each way and it's over lots of dips and rises and large cracks. The lava field is very uneven because the lava flows underneath and then breaks up from underneath, causing the top layer to crack upwards like small hills. The top layer of cooled lava gives you lots of friction so it's hard to slip, however it is almost like very tiny glass shards in some cases (you will hear it crunch underneath your feet), so you don't want to fall. I picked up a piece just to look at it and noticed i had small pin pricks that started bleeding... that's how sharp it is!
What to bring:
Wear shorts, t-shirt and some good hiking shoes (boots not necessary). Bring lots of water, some snacks or food, rain jacket, hat, sun screen, camera and extra batteries because you'll want to take lots of video. When you are hiking back, it will get hot if it's sunny and not raining. Chris provides walking sticks, hats with lights on them and even had toilet paper (i would suggest to bring some of your own just in case) and also juice when we got back to the cars.
I would also suggest some skin lotion, being around the lava where it's incredibly hot will dry your skin, especially your legs and face when the wind blows across the molten lava right at you.
This was such a memorable trip that if I go back to Hawaii, I would like to do this again with some other friends and will definitely be relying on Chris' services.