We got one for Christmas a couple of years ago, specifically so it would be what was jumped on, not the couch. We bought it at a sporting goods store, and it was OK for a while. However, the cover over the springs ripped quickly, and I was very uncomfortable with the exposed metal spring edges. It now lives in the garage and isn't much in demand. Was interesting for maybe 2-3 months. But then, we live in So CA so the kids can always play outside and they do gymnastics with big tramps all the time, so maybe it was just us.
I never had safety concerns about it until the cover started to rip.