People at my range bring them all the time.
In a a bolt action rifle with sub-sonic 22s the click of the firing pin is louder than the actual shot.
A bit louder in most pistols due to 22 pistols being straight blowback for the most part.
My range is humongous, so I don't see, but usually rather hear, people with them (not that you can always tell). Plenty of people in my neck of the woods seem to buy them, because there are a decent number of shops that promote them, and my LGS has a pretty big ass case dedicated to them, so there must be demand to keep that kind of stock.
So yeah, a canned .22 is gonna be close to movie quiet, and when I shoot my FNX-45 with subsonics, it gets pretty quiet, but I'm sure you can still hear it even a couple of hundred yards away. People not in the know might not recognize it as a gunshot. Otherwise, you pretty much have to tune your gun and ammo to get a can (semi) quiet. There's a pretty big difference shooting my .300BLK with sub and supersonic ammo.
One thing I find interesting is that so many European countries with heavy gun restrictions let you (once you have a license) buy a suppressor like it's a bottle of milk. I don't think they're even considered "firearms", and it's my understanding that they are even required at ranges in some countries for hearing safety.