Amazing experience with this tour. The tour allows access to the short line when entering the catacombs, which in itself is worth the price of admission. The tour group was small 12-14 people so we didn't need to use headsets to hear the guide who was knowledgeable and funny. It was also easier to follow the guide through some narrow or low areas without feeling squeezed by too many people. The tour also allowed access to areas restricted to the general public so we got to see some incredible areas that were not in your typical tour. Highly recommended for an insightful look into some really important history of Paris.
One note of caution. When you get to the catacombs, please make sure the entry personnel look at your voucher CAREFULLY to ensure that they know which group you are with. We arrived at 4:05pm for a 4:30 tour and were told they had left without us so we ran down the 150 stairs and rushed to catch up with a group that turned out to not be the correct tour group. We had to backtrack through about 10 minutes of tunnels. We ended up waiting at the bottom of the stairs for 30 minutes in the first staging area for our tour group who came along at 4:45pm or so. Bottom line--don't let the personnel at the entrance tell you that your tour left without you if it doesn't make sense!
Definitely worth getting the small group tour! You skip the lines and the tour guide was amazing! He took us into parts the regular paying guests don't get to see and was very knowledgeable about what we were seeing. He allowed us to take all the time we wanted getting photos and asking questions. Alberto was really a wonderful guide and would recommend this tour for any history buff!