Full DIsclosure: I have played through the entire Campaign Story on Heroic (The Way it's Meant to be played) via Xbox Gamepass. This review is for the Halo Campaign as Steam will not allow me to write one for that game, and I am not willing to purchase the campaign at this time via Steam due to the views you will find reflected here.

Gameplay
While I am a Halo Purist and do not believe that sprint is a mechanic that should be utilized in the Halo franchise, the maps in Campaign do support the mechanic more robustly, even if weapons now suffer a lack of variety you would experience in Halo 3 and prior. All but a select few weapons are effectively hitscan with some dropoff at times, but those that are not hitscan tend to have fairly strong projectile tracking. This leaves encounters stagnant and repetitive. Enemies are not particularly difficult to fight; even bosses are very easy to take down with a few well placed shots from the classic Sniper, or a couple fusion coils to the face. Endgame boss Escherum was more satisfying by far to fight than the final boss; Endless NoName. Endless NoName feels like a huge cheap ripoff of Doom Eternal's Khan Makyr. Design-wise, Lore-wise, and Gameplay-Wise she is so unbelievably BORING. Imagine just dodging shiny globe lights and fighting off normal waves of enemies concluded with a bullet spongey brute chieftain and that's all you'll need to know about that encounter. Most of the game outside of the story you will find yourself doing missions that have no consequences upon each other other than ranking up stats that max out post-story anyway, and finding mostly stale looking multiplayer cosmetics on Zeta Halo. I'll say that not all encounters are borefests. Many a time my eyes lit up as I progressed onward to a new objective and I thought "Maybe this time I wont punch a few panels and what I do will actually affect the world around me, instead of simply being told that anything I do mattered, it will be shown to me or expressed to me in a meaningful and non-superfluous manner." The most that changes is that "FOBs" will spawn a few marines and become active. But you won't see any firefights you didn't start. No patrols or marines to rescue later if perhaps they failed in a hypothetical recon mission. Marines you do rescue don't actually change anything, and simply follow you around like lost puppies.

Design and Setting
While we may have seen many a thing in trailers, here you will mostly be greeted with a deciduous biome populated with hexagonal spires and structures, interrupted by repeating Banished & UNSC structures that are never destroyed or really change. The map is mostly static, and while that may seem like I'm asking for a lot, this is an open world game now. If you don't want to simply be just "Another one" you have to do literally anything to stand apart and there is so much missed opportunity since the map is occupied by at least two actively warring factions. Gone is the design inspired so heavily by Issac Asimov's Foundation, and a perverse misunderstanding of it takes it place, devoid of variety, or any of it's own creativity. Nothing new is here, just more of 343i taking what you love and placing their grimy sticky hands on it.

Characters and Story
What
Huh
Who would have guessed that they wouldn't know what they were doing here?
Le Big smelly apes blew up le biggest human ship offscreen? Maybe? Le Abandon Ship. Hmm, so all the story happened before I got here?
Local Smartest Being in Galaxy says "My big stupid self" after realizing they are no longer redeemable whatsoever. Very le Smart. I screamed at this when I saw it, literally screamed in pain.
Cortana literally blows up le big angry monkey homeworld and then is upset when the biggest angriest monkeyman captures her and puts her in timeout. She also blew up le Opera House too. (Sydney)

Endlessly speaking of endless noname pops out of local halo superstructure and pontificates to main protagonist how much she's TOTALLY GONNA DO THE THING! Le protagonist does not even see LE THING OCCUR or WAKEUP or REVIVE. What did I even drink coffee for. That thing died like the star wars franchise. The Harbinger of literally buck all. Le Harbinger of bad storytelling is working with teh damn dirty apes, don't know why or how they met on tinder but it's not a healthy relationship.
Point to my rambling is that you learn nothing about what the big baddie is even trying to do.
Not fire the halo ring, I guess? Oooo the ring has secrets that you won't learn anything about anytime soon!
This is probably the most rambly spoiler tag you'll ever read and I'm so sorry. I'm quite nettled by how backwards this "story" is. Also my salamander is dying and I can't help him. :( It literally gives nothing but ENDLESS Questions, with no answers in sight. It just circles back, like an ENDLESS Loop.

The story is written by literal interns. Look up the writing cast, they are equivalent to Reddit moderators.

More concisely, 343 literally writes their character(s) into a corner in this story, and introduces useless plot elements that go unsolved. They put all compelling and exciting elements into audiologs and outside of the story entirely. This story is shrouded in a false sense of mystery, but when you pop the lid you just get an engine radiator soaked in melted smelly cheese and disappointment. Maybe there's a lore reason behind the vehicles being made from bouncy paper mache? Where do we get them from? Why do I need to pretend I care about mr Pilot? I hate him and I hope he dies soon. Then we won't have to rescue him from Donkey Kong again.

Will edit later. Forgive me for not reviewing the multiplayer. No I don't like it. Why are there only 7 maps? Why are there no custom gamemodes? Why do you offer no succor 343?