In general Thor's RVs are about the same as any other manufacturer's unit. All have some odd quality issue and occasionally they do produce a lemon. On the whole, though, if you go into the process "eyes wide open" and fully armed with information you'll be better off.
They key is make sure the dealer (Camping World--CW) is willing to work with you and not against you. CW does have a pretty bad rap in general but there are some that people have had good experiences with.
Thor, for many people on the forums here, has been excellent to work with and very responsive to most, if not all, inquiries.
When all else fails there is Thor's factory service in Wakarusa, IN that provides top-notch repair services.
Find a really good pre-delivery-inspection checklist (a good one can be found in Ed's crowd sourced Axis/Vegas manual here: http://www.thorforums.com/forums/f10...nual-4961.html
). Have the dealer take you through the unit going over the checklist before you sign any delivery paperwork and make sure you get in writing all the things that they will be fixing for you. In addition: do not let them hold it hostage: If they tell you they'll need to order parts inform them that you'll take the unit with you and only return once they have the parts on hand.
Having a bit of knowledge going in will make things run smoothly for you and help you weather some of the storm--if it happens. Read up on the forums here, and ask any and all questions you may have...there are lots of us who have been through it (good and bad) and are willing to answer questions.