Like most of the guns made in the Basque region of Spain, they're pretty well made. They are mostly copies of other - tested - designs, with an occasional design input of their own.
The biggest problems (of which I'm aware) was the metallurgy was hit and miss. One pistol would be dandy, the next rather soft in the frame and slide, so wear accelerated.
However, if you have one after all this time, it's probably a pretty good one. Don't over load it - they will handle full charge ammo, but no point in running it full charge all the time.