I haven't tried using them, so I have more of a negative prejudice than a negative conclusion. I believe they would work well as a speed aid, but not as a substitute for rigid ring spanners when you need to tighten bolts, because as a practical matter they lack the strength of normal ring spanners. I also think their advantage over sockets with regard to overhead clearance requirements is offset by their disadvantage with regard to radial clearance requirements. So, my tentative opinion is that they have two, fairly specialised applications, both as speed aids. One relevant situation is where you need to tighten a bolt in a confined amount of headroom above the nut or bolthead. The other is where you have enough headroom for a socket ratchet, but socket ratchets pull sideways off the nut when you pull on the handle, so you need to use your other hand to keep them in place. The ratchet-ring is faster because you can operate it ratchet-style with one hand.
I keep quite a range of hand tools to suit unusual circumstances, but I'm never in such a hurry that I can't use either conventional sockets or rings. A practising motor mechanic might find value in the ratchet-rings, but as a hobbyist I don't have a desire for them. (I don't even use half-inch-drive socket ratchet handles for applying any worthwhile torque to bolts, I run them down with the ratchet then change to a breaker bar if I want more than 20 lb ft of torque.)
