I have a set which I've owned for nearly 20 years, and never broken a tool. Great quality, look like they were made in the Snap-On factory. I like the concept of driving the nut by the flats rather than the hex corners.
Having said that, their Achilles heel is that they are both metric and Imperial, so they don't fit aas well as they should. This has 3 snags:
1) The sockets are physically bigger than they need to be - not good for confined spaces.
2) There is more movement required when ratcheting back and forth, due to the extra play - also not good for confined spaces!
3) They are more likely to round a bolt-head/nut than they would if they were a perfect fit.
I have subsequently found that several other good manufacturers (Snap-On, Hazet, probably Craftsman) also make "flank-drive" sockets and spanners, but without the dual metric/imperial sloppy fit. I'm happy with my Metrinch, but if I were buying again, I would go for a plain metric set from a good manufacturer.