Fun and puts the "new" into Halo and you.
As for the new enemies, the Prometheans, they are not to be reckoned with. While on the lower difficulties they may seem easy, but on Heroic and Legendary, they are buffed so hard, that you don't want to be even relatively close to their range of fire. The regular knights are more or less like your average Elite or so on that difficulty, but coupled with crawlers and a watcher or two as backup, you sure as hell want to stay in cover. The plan is ALWAYS go for the watchers, they not only throw back grenades you send at the knights, but can set up turrets and provide shielding for knights and crawlers. As for the crawlers, they are the Promethean cannon fodder, just one shot to their head is enough to make them go, but you always want to go for the snipes first if there are any as they are armed with Binary Rifles and can totally ruin your day with their one-hit kills. This is done by looking for crawlers that have a halo above their head as that indicates they are aiming.
As for the rest of the knight arsenal, on legendary, one of the most common ones you'll see are the Battlewagons. These guys pack a punch as they are armed with the rebounding Scattershot which has a slightly longer range than a Shotgun and WILL ruin your day if they get close enough, and they DO get close enough if you don't kill them quickly and they start running at you since they have a pretty large stride and will teleport-charge at you once their shielding is down (as would many other knights) and use that Scattershot if you aren't quick enough. The differences in how knights teleport-charge at you is very small, as most tend to teleport back within a couple seconds (which also has them regain most of their shields) whereas some like the Battlewagon will stay for a couple seconds as they have weapons that can easily kill with one shot.
The next knight class you'll see and which are rare is the Lancer class. These guys, like the Crawler Snipe, are armed with Binary Rifles as well and can also ruin your day if you are not careful. The final class of Promethean is the Commandos, these guys are also rare to see, and their weapon of choice is the Incineration Cannon, which is the Promethean equivalent of the Rocket Launcher, mixed with the rebounding effect of the Scattershot. This is also a one-hit weapon and use 1 shot a clip. Of all things, YOU DO NOT want to get hit by this. The best advice one could give with these guys is to be out of their range of fire and to kill all their surrounding allies first. Then when you attract their attention, you want it to be close enough to where they won't shoot, and far enough to not be ripped open by their melee capabilities. The rest of the enemies you'll see in the covenant are basically the same as previous games with only a couple species being left out.
Finally there is the stellar artwork of Halo 4 that makes it's campaign beautiful. I literally was amazed by the landscapes of Requiem and everything else. You could just stare at each level design for hours on end looking at it's never ending beauty. What really got me was in mission 6, you take to the skies, and you could see the land of Requiem laying just below you like you're looking at a mix of African savannahs and seas coupled with a dazzling sunset. Halo 4 is the epitome of graphical designing this gen, using the Xbox 360 to the best of it's capabilities. If this didn't sell it the next sections will. Now onto the best part of H4, multiplayer.
In Halo 4, the multiplayer really expands on the previous games. The ranking system is a nice feature, but can easily be abused by playing large amounts of Spartan Ops each day until you reach the daily cap. As for classes, you start out with default classes but they decrease as you rank up and gain customizable ones. You have up to five customizable classes by the time you beat your first 50 ranks and complete the regular spartan path and start working on specializations afterwards. Each class has an option for primary weapon, secondary weapon, grenade, armor ability, tactical package, and support package. There are many ways to customize your classes to fit how you play (you can even have each class prioritized for certain game types.)
The weapons are easy to get accustomed to if your a new or old player, the grenades are basic and can be used in any way you deem fit or effective, and armor abilities can level the playing field when used correctly. The tactical packages and support packages can provide little bonuses that can decide whether or not you're quicker on the draw when you and another person are reloading or can increase your shield recharge rate or give infinite sprint. As for game types, there are many in which you can play competitively or have fun screwing around with friends, namely when playing on custom-made games and maps.
Specializations happen when you finish your regular spartan career. These paths give you more armor and emblems corresponding to that specialization, weapon skins, and a specialization-only support or tactical package that is unlocked at the end of the specialization. Each specialization goes on for 10 ranks, 9 if you want to be technical, and your rank progression is stopped at the end of each one until you choose your next specialization. There are 130 ranks in all.
Now for spartan customization, most items will be required through mastery of certain commendations if not most, with the only exceptions being the items you get from the first 50 ranks, and special bonuses from entering codes on Halo Waypoint in which most if not some might require you to do something in-game first. The customizable things for your spartan is armor and it's colors and visor colors, the spartan's emblem and it's colors, your spartan's ID/IFF tag, and what stance your spartan uses.
The next thing to go over is Spartan Ops. This is a separate game type that changes every week and focuses on an ever-expanding story of the campaign. Each week there will be a Spartan Ops episode that comes with a starting video and five missions to complete. So far there have been five episodes, each with five missions each and they have been telling a brilliant story. There will be five more episodes in coming weeks as well, and each Spartan Ops season is to be a collection of 10 episodes. As for what I said earlier, Spartan Ops is the go-to method of ranking up as you get double the amount of experience you normally get (around 3K for regular, nearly 6K for SpOps) for every full game.
Finally there is forge mode, which this time around, doesn't have much differences from Reach if not worse. Forge however, while is largely about making maps, like Custom Games, you can mess around here all you want with your friends and is a fun way to kick back. Maps used in Custom Games can be maps that have been created and saved by you and your friends here in forge mode. Another game mode that can be used is theater mode, which allows you to save films and pictures of gameplay to where you can upload it to your fileshare to share with the world. And that my readers, pretty much sums up most of the awesomeness in Halo 4, and there are bonus features that can be used on Halo Waypoint that can help you in Halo 4.
If you haven't already, then get this now because it's a generation-defining game that can give you endless hours of fun and has many capabilities you won't see in your average multiplatform Call of Duty game. In the end, Halo 4 gets the Kane seal of approval and is a good game for newcomers and old alike.