Back to the original question:
I have one, have had it for a couple of years.
I like it, I don't regret buying it, and I have fun shooting it. Come out to a shotgun shoot and you'll likely see me shooting clays with it.
It is *NOT* my choice for a HD weapon.
Yes, it's compact and light, yes it's got impressive ammo capacity (14 rds if using "normal" shells, 20+ if using mini shells).
There's a downside to each of those attributes.
Because it's so short, the muzzle end is essentially even with your support hand at the end of the pump motion. That's dangerous. You have to ensure you have a SOLID forward grip or loop. You can find stories of people shooting their support hand accidentally with the KSG.
Because it's light, perceived recoil is much stouter. I tried some turkey loads in it once. ONCE. Not pleasant. Depending on your body mass you may find that 00 buckshot rings your bell considerably more than a larger shotgun.
14 shotshell capacity is a lot, but it comes with the price of multiple magazine tube administration. There are 2 separate magazine tubes. You have to switch between them. If you run one tube dry, you have to switch to the other tube *BEFORE* you eject the last shell from the first tube, or else you're going to get a "click" the next time you pull the trigger. If (heaven forbid) you get into a situation where you have to fire more than 7 rounds under duress are you going to remember to hit that tube switch immediately after firing, and before ejecting, round #7?
Oh BTW, that magazine tube switch has a "neutral" position that doesn't allow *EITHER* of the tubes to dispense shells. Yup, you guessed it, the neutral position is in the middle of the left and right tube positions. Hope the switch doesn't ever get set there accidentally when you don't want it to be.
The ejection port and the magazine tube heads are in the same space at the bottom of the gun. It is quite difficult to load a shell into a tube while keeping the gun in a firing posture; to do so, you not only have to push a shell upwards into the bottom of the gun at an awkward vertical angle, but you also have to angle it horizontally to the left or right to go into the correct tube (unless you ran both tubes empty). Do you remember which tube you were firing from? Got to load to that same tube... I've given up trying to load the KSG while shouldered - I flip it upside down to load it, and loading is much slower compared to a conventional shotgun.
Another annoyance is the shell keepers at the mouth of each magazine tube - they have a sharp corner that tends to catch and grab the fabric of glove fingers when I wear gloves.