I have toured the house a couple of times... most recently in March 2013. First of all it is amazing... a castle in the desert. Very different from anything else around. The stories of Johnson the insurance man and Scotty the con-man are wonderful. The building is beautiful.
The first time I took the tour (2006) it was first person... the guide was stuck in 1930, and knew nothing of more modern events... It was a spectacular tour. My teen age son had a great time as well. On my recent tour, the guide did not do first person, and when asked was a bit defensive... In all, he was not one of the best house tour guides I have seen, but even with a lesser guide the tour was worth it, and both I and daughter and friends had a blast.
In 2006 I took the underground tour as well... lots of fun, lots more information about the place... also worth it.
The castle is very different than other Death Valley experiences... It is a long way from other things... if staying in Death Valley this makes a good day with a loop through Beatty and Ryolite.