I've got the key version - same one as the first post. Mine is bolted down to the floor in my truck, and I also run the cable around the passenger seat mount. I think if someone took a big old crowbar and jammed it in there they could peel back the top, but it would require time... and I think most smash-and-grab guys wouldn't take the time.
I only use mine when necessary. If I'm on a road trip or something, I wouldn't use it - I'd put the pistol in a more accessible place, like the console. Overall I think it's a good purchase for ~$30 though. It's certainly not a "safe", but at least it's a lockable metal box that will slow someone down.