We have been using one for about two years now. It works pretty well for us. We haul a Toyota Solara. The straps that come with it are not that easy to use, as they are made to be used on several sized tires, and are just a little more difficult to use than the ones that are made for the size tire on your vehicle.
I wish the tongue was made a little different, as it is now, in order to keep the ball mount high enough to eliminate dragging going into and out of gas stations, the tongue slants uphill noticeably. Not really a problem other than esthetics. An RV with a lower hitch and less over hang that our 39' Winnebago would be fine.
The other issue with it is connecting the lights. The lights are made for systems that use the same bulb for brakes and turn signal. Our Winnebago has separate turn signal and brake light bulbs. We had to buy an adapter to make it work properly.
With the brake adjustment on the dolly, it takes a couple of times stopping to get it set correctly, but not really a problem after that.
Other than the items I mentioned we have pulled about 10,000 miles in the last two years without incident.
I hope this helps.
Paul
