I don't think it's bad, but ignoring multiplayer, I felt that:
Spartan Ops was a good idea that didn't really execute very well. The encounters were either boring or frustrating depending on difficulty, which was the only kind of customization afforded to the missions. There was very little replay value if you didn't care about credits, no theatre, no scoring, no skulls, etc. The story bits were mostly good in the cutscenes, but the in-game stuff was laughably bad with Palmer and Roland squawking in your ear the whole time about pressing the next button for the eggheads upstairs. It just wasn't even close to a good replacement for Firefight in the long run, and the weekly release looking back just seemed more smoke and mirrors than anything, since the first half-season came with the game and was locked arbitrarily. Not to mention, and this was a problem in campaign for me as well, the Prometheans are just not very fun to fight compared to Covenant. I like the idea of the units working together in different combinations, but there were only 3 of them, and every battle was basically Knight + Watcher with Crawlers running around. The Knight has some above average weapon, and the Watcher flies around blocking shots and grenades when near a Knight. Crawlers just run around aimlessly toward you. The Knight class were bulletspongey, and difficult to tell apart from one another as far as their subclass is concerned and difficult to gauge just how much shields/health was left on each. Knights being invincible when entering and exiting the teleport is bs too. They could definitely improve them going forward, and I really hope they take them back to the drawing board for Halo 5, especially if they're going to stay as a prominent faction, which seems to be the case.
Forge had quite a few problems and aside from shadows and magnets it was a pretty big regression from Reach. Same deal with Theatre mode, across game-modes. Same deal with File Shares - something that was broken for way too long after launch. Those three things had a pretty powerful negative effect on the Halo community at large in my view.
Campaign's story was good, if you follow the lore, but otherwise was too vague to understand for the most part, so you pretty much had to rely on external media or the Master Chief-Cortana thread to get something out of it. As for the gameplay, it felt mostly fine, but the encounter design has continued the downward trend off of Halo 3. I burnt out on multiplayer right around when champions bundle released which was probably not that long after I maxed out the SR rank, and across the board, I don't feel like there is much there to be worth really replaying, but I inevitably will when MC Collection comes around, hopefully that breathes a bit of new life into it for me. I bet I'll stay mostly hopping between 1-3 though, sadly. Here's hoping to the future with Guardians, anyway.
