4 years ago, this question has already been answered here. A lot has happened since then, however, most notable of which is the overhaul of canon to Disney's specifications and the relegation of the EU into Legends fanon status.
In the EU, stormtroopers are elite New Order clone troopers armed with deadly new weapons, blazing new ships and shiny new armour. In the new canon, however, they are just normal folks with none of the genetic modifications clones had. Anyone who has watched Rebels should know that the metaphor "shooting like a stormtrooper" exists in-universe.
So with this in mind, looking at the current Disney canon, are stormtroopers truly known to the Imperial public to be as bad in combat as the movies led us to believe? And did this change after RotJ?
Edit: Put it another way: So far, the only people I've seen talking badly about stormtroopers are people who have reason to - those with outright superior skill like Jedi, clones and bounty hunters, or enemies who basically hate them, like your common "Rebel scum". From the perspective of the common citizenry, however, do the stormtroopers suck?