I have one of the mag haulers from Cabela's. I've had it for quite a few years, and can't say enough good things about it.
I ordered it after killing a med sized black bear at camp, and spending most of the next day dragging it out by myself. The next bear I shot went on the hauler, and what a difference.
I've used it to get more than a couple deer out of the woods, hauling firewood, and a bunch of other things too.
The one I have is very well made, and has held up great over the time I've had it.
I've found it to be helpful to tie the legs of whatever critter you're giving a ride, up out of the way, or they always seem to end up in the spokes, and If you balance the weight over the axle, there's no added strain trying to hold the handle up, or pushing it down while you use it.
Mine is the model with the single wheels on each side, by the way. I thought about getting the dual wheeled model, but there hasn't been a time so far, that I wished I had the extra wheels.
Bob