I looked at a couple of Mandalays (in the 2005/2006 range) when we were looking for a coach. They were equipped nicely, but the quality just didn't seem to be there to me. Also, both had terrible looking cracking of the paint under the clear coat - mostly the darkest colors. One salesman tried to convince me it was supposed to look like that.
Also, on one, the main slide had been dragging and the covering on the bottom was worn off until the plywood was showing.
We opted to pay a little more for a Newmar and I'm still in awe of the quality and detail compared to a lot of other brands we looked at.
That being said, I'm sure Thor products are fine, but I feel there are others with better quality.