I have been a Halo fan since it originally came out. So I'm gonna break this down into a couple of parts.
First, to get this out of the way. From a lore perspective, this show is a travesty. It is so far removed from the lore as to unrecognizable if it were not for the character and place names. John is not even loosely based on the one from the game/book lore. Halsey is my either. In fact none of the characters save one is. Ackerson. He is the only character slightly lore accurate with his coniving and hatred of Halsey.
Now setting aside the fanboy in me. The show is not good even as a standalone. The story can not decide what it wants to be. It is chaotic and a mixed bag of cats. It can not show events in a convincing way at all. The fall of reach was delegated to a single episode of fighting and then we are whisked away to a different planet for some other goofy story.
At this point they just need to stop. Two seasons of someone acting out word vomit is enough.