I never was into Halo even when I had the console to play it on. But I still think it's one of the best franchises around. Sadly, it seems a bit down from the Bungie era, doubt 343 will ever be able.to elevate themselves to such high standards.
All I gathered from press reviews coming out of Gamescom, a lot of them had complaints about SP. Of course, those are all subjective views on a portion of the campaign.
The biggest gripe from some was a persistent 4 player squad even when playing solo (3 AI teammates), but paired with dropping of local co-op.