Actually, the 59/66 was very well made. My best condition 59/66 is probably my among most accurate SKS. I also have a Romanian and a Norinco that both shoot exceptionally well.
Functionally, the 59/66 has that gas valve. It shouldn't be a problem for you if you keep it clean and oil it occasionally though. It can be a real problem on SKS that were well used by the Yugoslavians. They tended to door poor maintenance after shooting corrosive ammo. Usually a new gas valve fixes it.
So, comparing a new 59/66 to other flavors of milsurp SKS (leaving commercial Norincos out of this discussion since quality can be spotty with them), I'd say the only drawbacks to the 59/66 are longer length, heavier weight and front heavy balance. Otherwise, it's just as good as any other SKS.
Oh yea, and there is that whole thing with no Yugos having chrome lined bores. Another reason why my Romie is my favorite.
