I've never used one myself, but from what I've heard the Muela knives are very reputable, i.e. good, comparable to Puma and Boker.
Most are made of a 440-series stainless steel or equivalent, which some object to - but the thing to remember is that it was mostly North America that caught up in the trend of designing modern super-steels.
European cutlers, by and large, stuck with the simpler stainless steels, and have, in their own simultaneous advancement, become very good at heat-treating them. So a Muela knife is quite capable of performing as a modern knife should.
I also know of one, the Magnum Alcaraz, that Pierce Brosnan's character carried in the movie Seraphim Falls, which is a very unconvention western and one of my favorites.