If I remember, a lot got cut out of 3. Including a Guardian level.
But anyways, Halo does have one of the worst fanbases in gaming. If anything is going to make me stop playing online, it's the people, not armor lock or jetpack. In fact, I loved armor abilities! They added so my h to the game, while still keeping it valences and simple.
But I really play for tbd campaign. And despite Reach "destroying HALO canon 4eva!!!1!11!one!" I found it to have a great story, that I can ignore a few minor inconsistencies with the books. Halsey's Journal fixes most of them, anyways.
So yeah. So far Halo hasn't disappointed me. Lets see how 4 turns out.