The Katana has a good reload speed which can give you a little breathing room in tight situations.
One major weakness of the Katana is that it has a shorter range than most other shotguns.
One must also note the Katana's fairly slow rate of fire, which means each round must count, as a missed shot can give enemies precious seconds to kill you or get away.
As with all shotguns, the weight of the Katana can cause problems. Some shotguns such as the Disciple and the M-22 Eviscerator are actually lighter than the Katana, making them preferable over the Katana for power-reliant classes like the Vanguard and the Adept.