Pretty good and very fixable to the ‘home mechanic’.
I’ve got the older versions on my bikes (one stealth one not). The non-stealth is on my awaydays ‘big’ bike, so doesn’t get the hammer that my ‘everything else ride’ hardtail.
The one on the hardtail is showing a fair bit of rotational play now. I have replaced the bushings, keys and the lot and it got much better, but regressed quickly. I think I might have worn the slots to the point where the keys are now worn by them and round we go. I put quite heavy grease in the first time I serviced it and I think this is the problem.
Also the cable freezes up in cold weather. The way to avoid it is to be careful when washing the bike and not to wash it upside down. This reduces water ingress into the frame. If there is water in the frame, it finds its way to the base of the post whenever the bike is upside down (trailside repair for example). It then trickles into the end freezes up.
They are way, way better than reverbs, though. There is much less to go wrong.