We did two tours with Yama, the red and the green. The tours are great in that you get to see a lot in just a day, the buses are nice, our guide and the other staff were lovely, the food was really good and all in all its good value.
I think the only downside is having to wait for other people on the bus. We stopped at (optional) pottery demonstrations, and one couple ended up shopping there for 45 mins while the rest of us waited, which was pretty annoying, and meant we had less time at actual interesting spots like imagination valley.
I recommend doing the tours, but if I go back to Goreme, I'll just go hiking and visit the museums by myself.