I can't stop staring at my invisible curtain rods!  They are amazing, hold up well under the kids pulling the curtains back and forth, and seem magnificent as they disappear into the banister of the ceiling. I hung the curtains in a way that hides the hardware as well. I don't think that the curtains can be too heavy though (mine are not sheer and ultra-light). I was nervous that any rods would make my quite low ceiling look even lower - that was not the case at all.  Highly recommend.