Coming from the iron barrel, 4 speed enfield,(1999) it was pretty solid. Its an old bike. But they will run well. It was smooth too. My triumph had annoying vibration. The enfield doesn't. Even at higher speeds (55-65). Its a well balanced single, that turns nice and slow.
Honestly, I never had any troubles with it. Just not enough power or brakes for bay area freeways.
I'm not sure about the newer ones. But you have to keep in mind you are buying a real classic bike, not a "Modern Classic." It may be made now, but its 50 years old.