This is definitely a must see! Get your tickets well in advance (I'm talking like a month in advance) because the tickets sell out fast and tours are small. The night tour is the best, some of the signs still light up and it's really cool to see.
The tour is an hour long and you must stay with your group but the guide gives you plenty of time to take photos. The guides are all volunteers and very knowledgeable. Overall this tour is a great experience and I highly recommend it.