I'm not saying it's broken. It's still great. It's just not... new. Not touching multi though, don't really enjoy Halo multi outside of drunken friend nights where we make up game modes. No firefight though? Lame as shit.
But I'm not saying similar gameplay, I'm thinking almost identical. New enemies don't really inspire different methods of playing, we're still fighting Covenant who act and play exactly like they used to, armour abilities don't really change up gameplay in any significant way... at least it's easier to see things, I guess.
I'm not really feeling it. But then, I guess I haven't been feeling it since Halo 1, so take that as you will. At least I kind of understand what's going on in the story, unlike Halo 3. I was completely lost in that game.