By the power of truth, I, while living, have conquered the universe.
I'm afraid that Reach doesn't just have the worst 'story' in the Halo series, it has one of the worst stories since the SW Prequels. It's a fact. People can claim to like it, but it's like a 12 year old school-child saying that they love Shakespeare.
So let's deconstruct Reach's campaign.
1) There is no plot until the end of The Package, and what can be laughably called the story was designed to shoehorn Keyes, Cortana and some Forerunner BS into the game as a shoddy way to try and bring the series full circle and make what can laughably be called the story look more important than it was. There is no depth to the objectives, it's just shooting at Covenant simply because they're there, the other games were at least creative with the objectives that had real significance. There's nothing exiting about it at all, only people with very simplistic minds can enjoy that.
So compare that manure to the Truth and Reconciliation, your objectives are relevant to your ultimate mission and it's exciting because you have a sense that there's something important to lose - Captain Keyes. It keeps the player involved in the game because there's something significant going on that isn't just a horde of Covenant.
2) The characters are so fucking dull it's not even funny. Each of them are a generic, one-dimensional archetypal -blam!-s. Bungie's biggest mistake is saying that Reach was about telling a human story, well they certainly went about it the wrong bloody way then! Spartans are not like ordinary humans, there is no way that the game can do a "human story" any justice when you've got Spartans as the protagonists. They should have stuck with Buck and have him with his old squad if they wanted to tell a human story because ODST had infinitely more likeable and believeable characters.
Then there's how illogically the characters act, this is glimpsed from the very start of the game where a Field Marshall acts out of character by fleeing from a fight. They know that this team of Zealots are there for a reason, but instead of allowing Emile to pursue the Field Marshall, Carter tells him to sit by the door for no reason, allowing the Elite to get away with data about this "latchkey" artefact at SWORD Base and ultimately caused a lot of deaths.
3) The soundtrack doesn't even compare to CE, 2 or ODST's. There are few good tracks at all, the choir is great and there was that one at the start of New Alexandria that was good, but the rest was nowhere near as memorable as tracks like Under Cover of Night, In Amber Clad or Neon Night. I'd almost call it dull, note the lack of any ambient tracks too. Bungie said that a big part of Reach was going to be making the planet feel like a character itself, almost alive... yeah, no. That never happened, it was BS all over again. I will use Truth and Reconciliation as an example again (because it's a perfect level), when you board the T&R you hear the whirring of mysterious alien machinery and get the impression you're somewhere totally unfamiliar, but also alive despite what the interior of the ship would suggest.
Most of Reach is a poorly derived copypasta of previous Halo game. It could have been done well, but it wasn't, I don't get why Bungie constantly rely on this nostalgia factor to try to make people enjoy some of their levels. It was completely bollocked up.
The opening of LNoS when you fight through the beach is a poorly constructed throwback to Silent Cartographer, the assault on the Ardent Prayer is more or less like the Truth and Reconciliation, as is the opening of Nightfall (which was an abysmal attempt to recreate the sniping section).
The Mongoose run is obviously based off the Warthog run from Halo CE and 3, like we've not seen that before. This could have been great, but there's no sense of danger at all. There are 2 Scarabs and dozens of infantry, but I can drive past in a truck at about 2mph without losing even half my shields.
The section where you hold out for Keyes is basically the bit from ODST's NMPD HQ level where you fight by the downed Pelican.
The Package is more or less a remake of the latter half of Uprising (from Halo 2) and Coastal Highway (from ODST).
Exodus is pretty much the only level that's truly original in the game.
I could go on and on and on here, but it's a fact that Reach is not a good Halo game. Halo has had the same "prequel treatment" SW went through, except that ODST and Wars were actually fantastic and Reach is left to stick out like a sore thumb as a stain on the series that can never be undone.
/rant
[Edited on 12.29.2011 2:13 AM PST]