I have no personal experience with them but a quick web search of the Cowboy forums turns this up:

The Taurus Thunderbolt has been a problem gun from day one, Taurus redesigned the original Colt design to make it easier to produce, unfortunatly they also made it harder to work on than an original and near impossible to time, Most of the complaints I've hears were either a round gets under the carrier which is hard to clear or of live rounds being ejected during cycling . I've been a cowboy action shooter for quite a while and I haven't heard of more than a couple guys getting the Thunderbolt to work. I don't know of any cowboy gunsmith that still works on them and the last I heard was that Taurus wasn't even trying to repair them but offering refunds instead.
I have an early AWA lightning that took a few trips to the gunsmiths to get dialed in, I've probably shot it in ten major matchs without a problem, I shoot it faster than any of my lever guns but I can see where the real fast shooters would have a problem getting one to run as fast as a well tuned 73.
Sorry I could'nt give you better new's, If you want a real earfull go over to the SASS wire and ask about it. http://sassnet.com
14delta

Sounds like "no bueno"...

Byron

We've got a couple here that you're welcome to play with when you come down. We certainly haven't wrung them out the way a cowboy shooter would, but ours have been trouble free.