I agree on this being the best first impression feel I've had. Good job to 343, who really have learned from Halo 4! After logging more hours into the game, and feeling pretty comfortable with it all, here's my overall impressions (thus far).

Positive

• The added mobility/clamber system makes moving around the map a joy!
  
• I LOVE that every weapon is filling more of their niche. This is something a lot of people are noticing. This is how Halo should be IMO. If there's a weapon on the map, it should have SOME kind of positive use.
  
• In a game of AR starts, I love spawning knowing I have a fighting chance. The pistol/AR combo are fantastic. Spawning in Halo 2 with SMG starts is like essentially starting with your hands tied behind your back.
  
• I actually love and feel good with the Spartans high-fiving each other, and coming into the arena with an attitude. It makes me want to do the same if I had people around me. Shame the majority feels otherwise about it because of weird social issues with "dudebros,"
  
• Spectator mode. Perfect for Halo.
  
• At first I thought the Sniper/DMR zoomed in to much, but then it made me realize why: They're better for bigger maps. I love this small difference of the DMR and BR. I hope the other rifles have something special about them that are unique enough to require them to be used as special occasions.
  

Critical

• I still think ground pound and the stabilizers makes the controller layout/learning/using routine super annoying (too much going on). I wish they'd either take them out, or combine them with other buttons.
  
• This is a complaint that can go beyond Halo 5, but I really, really wish I could communicate more with my random team mates. Even if all they're saying is dick jokes. Just make it easy for me to ignore them. At least make some kind of system that helps a player find friends to play with easier. It's hard to make friends on XBL when no one talks!
  
• The music when you die is pretty annoying.
  
• I CANNOT see a lot of weapon spawns. Please outline weapons or something.
  
• Networking issues. It's becoming more and more obvious that 343's weakness is networking, which is not what you want your weakness to be on a franchise like Halo. Please hire networking geniuses to patch this problem.
  
• Sword is a power weapon and needs to be strong, but I think it's just a little bit too OP.
  
• I know it's already being addressed, but flinch definitely needs to go.
  
• I'm unsure if sprint should be unlimited. I'm neutral on it. It's definitely fun to run around.
  
• I would love to be able to side clamber. Would that negatively affect gameplay?
  

My experience: 8/10. I'm excited what a year of polish will produce. Just please make sure we can be efficiently and quickly networked with each other at release. Please make that a priority, even if it means releasing the game 2 weeks early to people to stress test.