The Komodo dragon version of the monitor lizard makes a great pet in the sense that it is fun to watch them go about their daily routines. I visited a farm once where there were several of the large monitors housed in a large area covering several acres. I wouldn't exactly say they were pets, but they were enclosed and they were not afraid of humans.
I think they can make good pets for responsible pet owners. The lizards require some work. The primary concerns are making sure they have everything they need in their environment, and making sure they don't escape. A Komodo on the loose can be a dangerous situation.