Game worked fine for me and I loved it. Never really had issues outside of servers at first.
But I don't have any issues getting online now and I made it through all the campaign's without any issues.
The game had plenty of issues for you, you just didn't notice them and it's a shame. It has so many issues going from major to minor and almost every corner of the collection you look at has something wrong.
CE's netcode is just fucked as well as every single issue listed at
http://www.halobugs.com which makes the mode borderline unplayable online, especially when you're off-host. The aim assist is also completely non-existent compared to the original making Pistol fights much more difficult that intended.
Halo 2's netcode also has plenty issues but nothing nearly as bad as listed above. The campaign features a nasty desync bug (on all levels, not just Quarantine Zone) which makes getting through the co-op impossible for some players. One of the most minor bugs I know of in Halo 2 on MCC is that none of the enemies will dual wield weapons that they did in the original. I'm not sure if this ended up getting fixed but go and playthrough the Heretic level and watch how the remastered (and original) cutscene will show the Heretic leader dual wielding Plasma Rifles and then when you transition back into gameplay, he will only be holding one.
Halo 3 also has netcode issues (this is really becoming a pattern) but again, nothing as bad as listed above making the game a chore to play off-host.
Halo 4 funnily enough is the most functioning game in the collection but still features plenty of minor issues such as missing UI options in Forge for Trait Zones meaning you can't use the item at all, SR-1 showing on killcams despite the fact there are no SR ranks in Halo: The Master Chief Collection, loadouts randomly resetting, etc.
This also doesn't include the bugs like:
- the main menu user interface just completely bugging out forcing you to quit the game and in extreme cases restarting your console
- Matchmaking just not working forcing the player to back out and restart the search
- Party stability is a hot mess and often forces players to restart their game which causes even more instability for players currently in the lobby
- Maps failing to load
- No proper in-game emblem display for Halo 2 and Halo 3 - not allowing players to see who is who in Halo 2's Multiplayer
- Halo 2 Anniversary's microphone indicators overlapping and just looking god awful in general.
- Random game crashes
- The 343 Industries/Microsoft Studios splash screen literally jitters before you even see the main menu, forcing the main menu music to start playing early and overlapping the splash screen audio
I could go on and on but you'll run into these issues just playing casually.
I'm not meaning to go after you in this post but I hate people (in general, not specifically aiming this at you) saying that run into no issues and play this collection without issue when most times they get these issues and just shrug it off, restart the game and try again.