They may or may not be good, I haven't gone exclusive with them but have used a lot of them on solid 12 and 14 AWG for maybe 5 years or so. Haven't had a call back and found one to fail yet. Though they are supposed to take stranded wire as long as it is not fine stranded, the few times I have tried to insert stranded wire at least one strand wants to not cooperate - so I don't ordinarily use them with stranded - have used "lever lock" style on stranded a few times though.
One has to realize just because something is new doesn't mean it is all bad. Auto mechanics from 50+ years ago would think the aluminum engine blocks we have today are junk. There are some drawbacks I would imagine, but look at how much horsepower they can pack into a small space today and how much more efficient they can be - when they are working properly.