I have no idea how good these are, but be aware of underground wires before you pound your stakes in the ground. This summer some dude was doing exactly this, and hit a buried hot wire. Needless to say it didn't turn out good for him....Just a thought.
Mine work fine if they are tied down and kept free from snow loads. If not, they will fall or get blown away. Make sure all the pins are in place because they move around a lot, and will pull the frame tubes out of the joints (and then fall) if not pinned.