I have 300TDi auto and it's great for off-roading, but you must select a gear similar to what you'd do in a manual, don't just use "D"
The only slight whinge that I have is that 1st gear (even in low) is too high a gear for serious downhills, were-as in a manual it'll hold it back, in the auto you'll need to use the brakes as well.
New off-road drivers will enjoy it to, as they can concentrate on where they're going rather than if they're in the correct gear or stalling just at the wrong time. g for it!