-snip-Halo 3's campaign is my favorite by a mile. Everything screams epic in it from taking on a scarab in a tank, to fighting a scarab in a mongoose, to fighting 2 scarabs at once in a hornet, to Forward Unto Dawn dropping down and bringing more tanks to slaughter everyone.
If the scarab was actually hard to kill, I'd agree with you. But it wasnt. And with the tank on the ark it was only that much easier. And although fighting two at the same time sounds tough, the hornet is the most op vehicle known to man so taking them down was more of a fast chore than a fight. And overall, the levels themselves were short and somewhat more linear than CE or 2 (Something that was fixed with Reach) the Flood got majorly nerfed with how they'd crumble from a single punch, the pure forms were more annoying than challenging or fun. We stayed on earth to 'finish the fight' for only a few levels before bungie pulled a halo 2 and sent us into across the galaxy and there was no real moment that felt like the diorama or any sense of urgancy that the covies were dominating earth. (If the story involved us going country to country hunting down the prophet for a few more levels before the jump, that would've been so much nicer) And where was Gravemind? It's just so lame how we never really got to fight him and Bungie's excuse was that the cortana level was made out of gravemind (despite it's now known there was a planned boss battle with gravemind)
Even the final warthog run felt odd because you're driving on exploding cardboard the whole time. It felt like a quick memory crashgrab at what made Halo CE's warthog run so amazing.
And after the release of Gears of war and Crysis 1, hell even CoD4, graphically Halo 3 just didnt look that amazing even for it's time. The lighting was baked and uninteresting, the character model details were low res (ESPECIALLY Lord Hood) and everything was made up of low poly counts making everything look so flat. And when compared to the Halo 3 reveal trailer (which was real-time. Bungie confirmed they had a showcase for it) the overall quality took a noticeable drop. Though the overall artstyle is appreciated. Hopefully if Halo 3A becomes a thing, we'll get something that feels more up to date. (I say H3A because I refuse to accept the MCC version in it's broken twisted mess)
And if Halo 2's cliffhanger wasnt enough. BAM! Legendary ending with the dark planet (to be continued 5 years later with Halo 4) So much for finishing the fight...
But once again. I didnt down-right hate Halo 3's story, especially not when compared to 5, I just felt it was one the weaker stories in general. Nothing will ever beat the moments of stepping on Halo for the first time or nuking a covie ship with their own bomb.