Heres a few thoughts about halo 5 off the top of my head, this list is by no means complete and some of these may be opinions but i believe they are perfectly valid.
The good
Backdrops/skyboxes and enviroments are beautiful
Music, soundtrack, sounds and voice acting are great. i love the throwback to the classic halo theme.
Solid gameplay, its not perfect but its really good
High XP
Edit: sorry accidentally clicked post