Let’s begin with the movement changes and implements. The changes are fantastic, finally a Halo where I feel like a Spartan of the books/universes lore. I feel powerful, agile and fast. There is a satisfying thud when falling or leaping a great distance. Clambering added an element of interaction with the environment that was absent in older Halo games. It feels right. The thruster pack, which was always present in some form in the books, more so as stabilizers and adjustment in low gravity environments, but they where there none the less, are finally getting a more defined role in the Spartan 4’s arsenal. Even the Spartan II’s had “thruster” packs starting with Mark V. Overall I am pleased with the movement system, now let’s discuss weapons.
Everything feels solid, and plays well where it’s supposed to. The SMG is good at close quarters and the DMR at range, respectively. I have yet to feel as if I have been beaten unfairly or that someone has a massive advantage over me, and I feel like I always have a fair chance. The weapon balance seems exceptional and I’ve yet to see any major imbalances, but to sum things up:
I am pleased overall with the core mechanics, though I have major gripes about armor customization, seriously, it needs a lot of improvement and the lack of attention to it will cause backlash with many in the community. Aside from that and some aesthetic changes I’m not fond of, I will say kudos to you 343i. Halo 5’s beta was an absolute pleasure.
Edit
Some things I would like to see with the full release, how about we take the Spartan charge one step further, say a warthog is coming at you head on, and you know you can’t dodge it (which is unlikely, but still) say you could Spartan charge straight into it, sacrificing yourself but causing massive (or a decent bit) of damage to the hog. You are a soldier wearing a massive suit of metal after all, it only makes sense. Also, let’s not take a step backwards with armor, but forwards. Give Halo 4 level of customization to the player again, but instead of throwing a million armors at us, have sensible, role filling armors like EOD and Recon, but give each set of armor a lot of care, and dedication in the design process. The armors I’ve seen so far are great, but let me mix and match like I always have. As for smart scope, it’s good, it makes sense with the Spartans heads up display, and you don’t have to use it, ever. I’ve played entire games seeing if I could do just as well without it, and I had no issues doing so.
Keep in mind this represents my opinion and mine alone, thanks for reading, and fix that -yoink- armor customization. 
Thanks,
ZackS11099