I have used shotguns for hunting and competition more than 60 years, used them often in my LE career, and have taught hundreds of officers in defensive use of the shotgun. When people ask my advice on a home defense firearm, I will most often recommend a pump shotgun, unless they are a proficient pistol or rifle shot.
I have been present twice when a suspect was shot center mass at close range with 00 and that ended the aggression. At the ranges present in most residential rooms, the shotgun is a devastating fight stopper. There is a definite psychological effect on miscreants when the shotgun is deployed.
Most of my experience has been with Remington 870's or Ithaca 37's since that is mostly what most LE agencies have used over the past 70 years. LE training doctrine calls for the shotgun to be carried with the tube loaded and an empty chamber, with the safety "on", in what is called the "cruiser safe" condition, to minimize the potential for negligent discharges. The gun is charged when responding to a perceived threat.
A lot of my students over the years thought they knew how to operate a shotgun until we put them under pressure to load, reload, and operate the gun in a combat course of fire and they all of a sudden became all thumbs and forgot there the controls are. You have to practice with these guns.
Users must practice releasing the slide lock and the safety in order to chamber a round and fire. Semi autos that are not maintained properly are prone to malfunction more so than pump guns but any can fail. Any shotgun requires training and practice in manipulation of the controls and action as they are not intuitive. Recoil is a problem for some shooters but the effects of recoil can be minimized with proper technique. I am comfortable with them. If I knew I was going into CQB, my first choice is my 870 with #4 buck.