We have had ours for a whole 12 days.
We had very few items that need addressing during our PDI. The two big items turned out to be non-issues that were caused by the dealer's PDI guys. They accidently placed the Truma tankless hot water heater in clean mode, which took the service personnel a while to figure out. They also managed to lock the induction cook top, which made it look like it was broken. After service changed out the cook top we discovered the secret of locking and unlocking the cooktop.
The bad news (In my Opinion) is the bed mattress sucks eggs, we replaced it after sleeping on it one night. The second item that had to go was the J-Sofa. Fleetwood offers an optional sleeper sofa in place of the J-Sofa, if money was tight that is the way I would go. If funds are available order it with the J-Sofa, then rip it out and install theatre seating like we did.
I've driven the rig about 600 miles so far and I love it. Compared to our old 08 Expedition with the 6.7L, the Discovery is just so much nicer to drive. The longer wheel base makes for a smoother ride and the ISL9 certainly has some spare giddy up. Cruises very nice at 63 MPH. I'm hoping the fuel economy will be about what we were getting on our old rig, 8.5 mpg after the break-in period.
Overall we are very pleased with the 40D and looking to take her out every chance we get.