I've gotten back into Reach recently, and I've actually never completed the campaign, so I felt compelled to do the challenge and finally beat the campaign. I have to say that I didn't have half the fun I had playing previous Halos... I'm not sure if it's because I haven't played Halo single-player in a while, but the whole run into an area, defeat waves upon waves of enemies, and then repeat wore thin after the first few missions... I mean, it was bordering on predictability by endgame.
I also really disliked the general uselessness of any A.I. companion in the game, especially with the ill-equipped teammates like one member of Noble six who seemed to have a fucking shotgun in the goddamned grand canyon. Completely useless for any and all parts of that mission since everyone was basically long-range on that level. And them also being attached to your hip meant that flanking an enemy was impossible. Or they were caught on an object or chilling way far back from any point of interest.
All that said, I did have a lot of fun with the campaign and learning what happened before the original Halo (since I don't read the Halo books), but I'll never touch it again. The 10k xp points were pretty ace though.