It works very well on my 12-string acoustic, no buzz and no pressing too strongly to go out of tune. The rubber material seems really good, not too soft, not too hard. The build quality is very good. However, there are other products that are much more easy to handle with one hand, so if this is important for you, try some other brands and construction styles as well.
Overall, I like it but I seldom use the 12 string and I do not have to change the capo position between songs, so the minor handling issues are not a problem for me.