We bought our 2015 Challenger 37ND last February and the only problem we have is not having the time to take it out enough. We took four trips last year averaging 1 or 2 weeks and 800 to 1,000 miles per trip. We had a slide problem on the shakedown cruise where a wire came loose from the slide motor due to a bulb seal missing. Thor reimbursed me for a mobile tech and sent me the missing bulb seal for replacement.
My coach is currently in the shop for its first and only warranty visit and the items are all relatively minor. In fact if I didn't need a generator and chassis service and state safety inspection I may have just bit the bullet and repaired the items myself. Right now the dealer is waiting on the parts for the step recall.
For me, Thor Customer service has been outstanding which is something that was non existent with my Forest River.
The coach handles very well and we enjoy the space inside as well as the outdoor kitchen and entertainment area. We are already planning a four day trip in March and another 2 week long trip in April.
Overall we are very pleased with the Challenger.
FWIW, here is the link to the thread I posted on our trip to Charleston, SC.
If you go to the camping pics thread you can view some pics of Challengers setup for camping.