I think it depends on how the shooters are introduced to the round. I see many people use the words ".357", "snubby" and "pocket revolver" together way too frequently (in my opinion). Not a good combination for making a pleasing first impression on inexperienced users.
Are my .357s loud? A little, sure. I've had a range full of "kids" shooting semi-autos stop to see what was making all of that noise before. (I'm 30, as point of reference for my "kids" comment.
) But I personally find the ever popular 16" barrel M4gery .223s to be more obnoxious to be around. And the local PD uses .357 Sig chambered Glocks, which seem to be just as loud.
Does it kick? More than my 9mms, yes, of course. Pick a K-frame or larger revolver and it's manageable. Proper mindset and practice goes a long way toward not worrying about a little bump in the palm from the pistol. One thing to keep in mind is a lot of folks in my generation are accustomed to 9mm handguns and .223 caliber rifles, so anything that starts going up the horsepower scale is going to move them around more than they've experienced before.
Muzzle flash? Oh yeah, no getting around that one. Modern defense ammo may be pretty well flash-retarded. My reloads with 2400 powder, not so much. No getting around this one with full-power reloads I fear, it's going to get a bit bright. To be fair, a heavy dose of Power Pistol through a Glock 26 is pretty spectacular as well, just not quite as high up the "OOoooooo" scale.
Funny thing is, I came into the .357 late after having a fondness for .44 Magnum revolvers. Once the first K-frame came home, the 629 found itself in the safe more and more. Then the L-frame sealed the deal. No more .44 Magnum in my house. My 9mms may match the ballistics of the .357s (cherry picking here, 127gr Ranger SXT 9mm +P+ versus 125gr Golden Saber .357) and I will still say a .44 Magnum is more versatile, but depending on the question a .357 may be a perfectly good answer.