The system they label Quadra-Drive II is, and has historically been, one of the most capable of the computer-aided traction control systems, and it earned a nice writeup in the VDEG. You have no good idea what combination of things the truck is doing to get you traction and keep you safe, but it seems to work well. Along with Hill Ascent and Decent, the addition of a lot of ground clearance from the air suspension and the option of comprehensive skid plates from the Off-Road Adventure Group II puts recent Grand Cherokees real close to the top of the factory-ready off-roading SUVs/
The biggest strikes against them is rather poor reliability and there's not room for big tires without a lift. No truck is perfect, however, and they are a relative bargain when compared to a Range Rover or Range Rover Sport, two other off-the-shelf capable SUVs.
That said, the "OVERLAND" badging is mostly marketing. You can just as easily buy the one-step-down Limited and option it to end up with the same things that come on an Overland, or you can buy the higher-level Summit to get a few more standard goodies but still have the important stuff..