They aren't total pieces of junk. Far from it. But romping through the woods on rough, steep, or muddy trails is not their strong suit. Farm chores, utility vehicle for maintaing large facilities, it does pretty well. But there are much better choices out their for the deep-woods scrounging crowd.
They handle steep trails or otherwise better than anything I know of, and they will do it pulling their rated load and more. The real problem is a major lack of ground clearance, which can seriously hinder rough. A six inch log across the trail is a show stopper. I don't have much experience with mine in mud, and for the most part it isn't something I have to worry about. When I have encountered it, it hasn't been a problem. I don't go in deep mud with my equipment for any reason.
Some people like to complain about the 25 mph top speed. I don't see it as a problem. No way I want to go flying through the woods or fields at high speed in any UTV. That's for the kids who don't know any better and heal faster than people my age.