We bought the F350 version last December and have been very pleased so far. Only got 2K miles on it so I cant really comment on Mileage yet.
The trans shifting is a little different than the old truck, but no complaints, especially after the trans has some use / "learns".
The engine has plenty of torque so we're definitely not worried about pulling the RV, even in the mountains.
The better half likes it more than our old 2006 F350 with the V10. It is easier to get into, the seats are little more comfortable and the ride is better even with the tires inflated to recommended pressure.
I would strongly recommend the 7.3L / 10 speed combo.