Okay, okay, as usual, it's not the Holy Grail. As you might expect, it's solely a short-range weapon - if you go around trying to shoot people across sniper rifle distances, the AI will probably laugh at you. But in short- and medium-range battles - the most common sort - the shotgun can work wonders.
If you've used a shotgun in an FPS before, you probably won't be terribly surprised by this one. It packs a massive wallop at point-blank ranges, and the massiveness of it decreases quickly the farther away you get. Even the mightiest enemies - your friends in multiplayer, Covenant in Legendary, etc. - usually cannot withstand more than one, two, or at the very most three shotgun blasts, from close enough to touch them with the barrel. But take a step backwards, and you'll need to give it a little more, and if you're across the room, well... it's another story. However, if you
- Are inside
- Can see your enemy
It is, however, definitely a close-quarters weapon only. The only real use it has if you're going to be outside (unless you're a very in-your-face fighter) is for vehicles: it's one of the only small-arms weapons capable of doing enough damage to take out a Banshee or Ghost.
Sadly, there is one serious drawback (aside from range) that cripples the shotgun and can cripple you. The thing takes forever to reload. Shotguns usually do, of course, but that doesn't make it any more reassuring. Fire yourself empty, and you'll find that standing in one place, watching your metal thumbs shove each of the twelve 8-gauge shells into the loading port is an experience that may sour you on the shotgun for life. Keep an eye on your magazine, and try to reload whenever you get a chance - if you do it often, it will only take a moment, but if you put it off, rest assured - it will take matters into its own hands at exactly the wrong moment, and lock you up for longer than you'd like. The one redeeming quality of this is that, unlike most weapons in Halo, the shotgun's reload sequence isn't required to run from beginning to end. That is to say, while reloading, you can pull the trigger at any time and fire off whatever you have left. So the reload time isn't as big a deal as most people tend to think. Still, it's a good idea to keep a good backup weapon around for those moments - as the shotgun's melee speed falls just short of very bad.
A word of warning: in some areas, shotgun ammo can be very scarce. Use a careful touch with the trigger, and aim well.
Pros: Very large damage, area-effect shots, very large damage, very large damage, v - did I mention it has a very large damage?
Cons: Nonexistant damage at long-range, very lengthy reload times, barely adequate melee speed.
Usage: CQB! That is to say, Close Quarters Battle - only. The closer, the better - shove it in their face! Remember those headshots. Carry a good long-range weapon with it, hopefully one that works tolerably well in short-range circumstances as well, so you can use it as an out-of-ammo backup. And as much as you might like the shotgun, switch guns when you get outside.
For: The few. The proud. The brutal.