I've had this mount for about two weeks now and I'm pretty happy with it. It installed very easily onto my Jeep's factory bars right out of the box. Securing your bike is as simple as tightening the large red knob at the front to hold the front wheel, then tightening the strap over the rear wheel.
There are no real complaints. I would just recommend thinking ahead to the ease of a roof mount. I'm relatively short (5'6") and it's a chore to load/unload my bike on my '97 Jeep Grand Cherokee. It's easiest with a small stool or something for me, but it's still not graceful. I went with a roof mount because I use my rear hatch too often to have a rear mount system.
Overall, I'm satisfied with the product.