Oh mah dude! It was so bad. Halo 4 and 5 worked technically speaking, however they had content issues for days. Things like Theater and Custom games were gutted, and there were so many missing game types you could fill a school district with the milk cartons.
Content and variety were huge issues for both games at launch. The MCC I can understand, but those mainline games? The amount of stuff missing was ridiculous.
All that said, I'm pretty optimistic for Halo Infinite. I just hope they don't completely 69 the movement system.
I remember Halo 5 not having BTB (and when BTB did come online, it felt like a bunch of low budget forge maps), a crappy and buggy theater mode and no forge mode at launch, but I don't remember any issues with Halo 4. I felt that Halo 4 was a full featured package from day one. I thought the theater mode is Halo 4 was fairly robust, with the only feature taken away was the ability to film the campaign. While Halo 4 didn't have a few multiplayer modes from Reach, it added Flood, Regicide, Dominion (loved this mode), Extraction and Ricochet. Halo 4 didn't have Firefight, but it did add Spartan Ops. So it all evened out.
I originally thought the Spartan Ops missions from Halo 4 were decent, but nothing great, when compared to the missions in the Halo campaigns up to that point. I was just playing through Spartan Ops the other day in MCC and I actually found the story, characters and level design better and more interesting when compared to the Halo 5 campaign and I was actually enjoying myself.