When I first saw these, I got quite enthusiastic. Then after some thought, decided against.
As detailed above, the risk of tilting is there, and once it starts to tilt, you won't stop it, but instinct may have you jumping in, and getting squashed.
Ideally this is a lifting tool only, then stands would be used. Great for most cars where a central lifting point is difficult.
After its new springs a couple of years ago, my Panda now sits higher than it did, but still I don't think one of those would fit underneath. Having to lift it a little each side first, before using this beam seems a nonsense, might as well just lift each side, one at a time, and sit it on a stand before lifting the other to match.
For older vehicles with greater clearance, this might be useful. The classic Panda is quite high at the rear, so that could be useful there, although they do have a central pad for lifting.
Personally, I think this is in the category of a great idea, a pain in practice. It'll get used once or twice, then sit in the garage unused.