>They are unusual. I've recently moved to a house with round door knobs and we often find them very difficult to open as you can't get a grip. I'm renting this but if I owned it I'd bin them all and put in levers.
When we bought this house, the first thing we did was to replace the doorknobs with handles. These still aren't European style handles - you have to turn them 45
o, not 30
o, and they work even if you lift them, but they work. This has saved us a bunch of effort while moving - we still have the necessary skills, so opening the door with your elbow and closing it with your heel while having your hands full was a breeze.
Still, inside we have doorknobs on all of the doors - just didn't bother to replace them, and actually you can't find a simple door handle. Ornamental, fitting for the front door - yes. Simple one for the inside, no.
Truth be said, American doorknobs work quite fine, still haven't seen any one of them getting regularly stuck. They work really smoothly.