If you're reading this, then chances are you either:
Campaign: I've been a big fan of the Halo franchise since Combat Evolved first launched, and I've followed the story like it was a really good book. From what I've witnessed, I'm somewhat in between happy and disappointed. The game opens up the same way as it was during the VGA awards last year, with the introduction of Noble team and their newest member, Noble Six. For the majority of the game, (s)he is always quiet, only talking in short sentences when, essentially, ordered to speak. I won't spoiler the rest of the story, but you'll love and hate it.
One thing that I didn't like about the campaign is that on some rare occasions, you feel rushed, having to complete something with no time limit, but all objectives that require doing something like defending an objective, escorting someone, or stopping something from winning all feel as if you can't fail (I waited for a long time on the very final part of the last mission for the Super Carrier to fire the shot and it didn't do anything.)
Campaign score: 7/10. Not the best campaign from Halo, but it's one that's still fun to play.
Multiplayer: Ah, what we all are playing for the majority of the time in Reach. The multiplayer is incredible as expected, but it ain't perfect. The multiplayer experience is amongst the best multiplayer games of 2010 that I've ever played. There is a type of addictive factor that simply seeing that piece of armor/upgrade that is either hilarious or absolutely badass makes you want to earn a vast amount of Credits. At the time that I'm typing this, I'm at a Major Grade 3, and I have my eyes on that Mark IV helmet. And further more, once you get past Lieutenant Colonel, there are much more items to purchase after that one rank.
Now that I'm done with the awesome armor, now onto gameplay. The shooting mechanics feel very smooth and comfortable, making a newb at Halo feel right at home. When using any type armor ability, you feel powerful in every way, whether you're using the simple (and my favorite) Sprint, or becoming a gunfire/explosion/fist sponge in the Armor Lock ability. And for those who think Bungie haven't addressed features that plagued Halo 1-ODST, fear not, for they have fixed and improved just about everything from all of the Halo games.
However, just because they fixed a lot of features from past Halo games, doesn't mean that it's perfect all around. For instance, you still have those classic "Halo moments" in Matchmaking games, like dying randomly from a Plasma Grenade thrown across the other side of a map, or getting killed in a situation where you should've killed your killer. It may be different, but it's still the Halo we all know of.
And speaking of dying randomly, the spawn system is absolutely broken beyond measure. In roughly 2/3 of all the games I've played, I've died and then spawned either dead, behind someone, in front of someone, they'd spawn in front/behind me, or some other ridiculous ways that I forgot about. It frustrates me when I get a spawn that results in the other team gaining, technically, two kills in a row from my deaths. In fact, I've documented all the worst spawns I've ever had in my File Share (gt: Whiplash x360a). If Bungie takes the time to fix the spawn system, then most people will feel much happier and less frustrated.
Another feature that irritates me the most are people exploiting armor abilities. One example are, for me, people who exploit Armor Lock. What I'm getting at is when people run up to some chum and melee them, they attempt to hit you, you hit Armor Lock, and you melee them back. It completely annoys me when I die because of this utter bull shit. One of my friends on Live (a Moderator in another forum) believes that people who use Armor Lock mostly want to frustrate people that are CQC happy, and I have that same idea in here. I mostly see people use it for this one purpose, when it should be used to distract other players to draw the attention towards you and not your team mates or to destroy a charging vehicle.
Multiplayer: 9/10. If you love multiplayer, then this is for you to sink your teeth in.
Forge: Ever since Halo 3 came out, we had access to the most awesome media and creativity that is Forge. Before, there were glitches (both helpful and frustrating) that made it both fun and hard to use. In Reach however, everything, like the multiplayer, is improved. Unlike in Halo 3, where you'd have to use certain glitches to make objects, say, float in the air or merge objects together, everything is, and I say again IS available to you in Forge. Say you want an object to just float with the object having collision boundaries, then you can use the Fixed object property. If you want an object to merge with another object, then you can use the Phase object property.
Along with these new features comes new objects! From spawns to buildings and scenery, this is basically Forge 2.0 in Bungie's final Halo game. I've yet to see something that I don't like, but it's freaking awesome!
Forge: 10/10. Incredibly addictive to use and it's super fun when you play these maps with friends in Custom Games.
Firefight: Back in ODST, me and my brother would play Firefight to just pass the time or to just screw around. In Reach, it's super revamped and much more awesome.
In ODST, you could only play with friends either on Live, or split screen. But in both situations, you had to be in a party in order to start a match. In Reach, you can now go into Matchmaking and play Firefight with random players over the Internet. In a bold way, every variant of Firefight have unlimited lives and only play through 1 Set (5 squares, one circle). Sure, it's there so that players don't just use this to boost Credits, but it would be very fun to try and survive an onslaught of never ending waves of Covenant soldiers.
In addition to Firefight in Matchmaking, you can also host or join a Custom game of Firefight, with similar game settings that Custom Games have. However, this to me is a lesser reason to play Custom Firefight, as you can have the settings set to Invincible with 300% damage, and just get every achievement that is Firefight specific. I literally got all the Firefight achievements in one Custom Firefight game on Corvette.
Firefight: 7/10. Matchmaking Firefight has a much higher replay value than Custom Firefight.