I have one.
Upsides - pretty simple, not too hard to assemble, will throw a good distance, pretty good variability in terms of high or low birds
Downsides - tends to bounce around unless you attach it to a tire or something, no way to set it up so that you can be a fair distance from it when it throws, so you are aways shooting at a target moving away from you - never a crossing shot.
Mine will throw doubles using Lowry targets. Top Flight targets from wholesale just shatter into shrapnel when I try to throw doubles.
Generally a good purchase, fun toy. One day I might either buy a simpler one, or jury rig something so I can shoot at crossing birds
Fat