We have a 2006 1150 we bought new. The main thing I would look for is water intrusion. Especially around the skylight in the shower and the front cap seam on the roof. Both are not sealed well from the factory and leaked on ours since almost new. The skylight over the shower has no curb and any crack in the caulking will allow water straight in. Really crappy design.
Other than that the main structure of the camper has held up well. I am typing this in the camper now near the Washington border headed for Alaska. We near full time our camper and it works well for us.