Alright, after spending about 2-3 hours in weapon drills and bot training testing weapons and 2 hours of arena, here we go. Obviously this is extremely opinionated feedback based on myself who has played since Halo CE and competitive Halo since Halo 2 - 3, than some in Halo 5. I’m a competitive player.
Console: PC
FPS: 100-135
Monitor: 1080p 240hz (locked to 144hz)
AR:
The AR feels pretty decent. Bloom at a distance feels pretty balanced. It’s always been the primary halo start weapon that shouldn’t be a “go to” weapon for an entire match. Which currently it feels like it is the go to weapon for an entire match, unless you manage to snag a power weapon or a BR. Depending on distance At close-med range, it takes 4 seconds of full spray while on head while slightly pulling down to kill. At med-long range, zoomed in it takes anywhere from 4-7 seconds to kill depending on the bloom accuracy your awarded with. So far the best use of the AR I’ve found is to full spray for 3-4 seconds, switch to pistol and spray and pray for the last 2 shots to be accurate (1st shot accuracy seems to be real unless they’re extremely far away which on the current maps we have don’t seem to be an issue because lines of sights are all super short.) If 2 people are fighting only with ARs, and each have decent tracking skills, all fights become a spray and pray because of bloom at med-long range engagements, at short range it’s whoever has best head tracking skills which I actually like. Something I found interesting was it takes less time to kill someone shooting them in the legs then it does shooting them in the crouch and letting the recoil kick up to the chest (what’s up with that?) This makes jumping sketch in this Halo because if they’re tracking your chest and you jump, you’re actually given them free damage to a more vulnerable body part, at least this is what I’ve seen so far with the bots and the 45 mins of slayer arena with live players.
Pistol:
Pistol is absolute poop. There are going to be a bunch of people that are going to disagree, and I’m seriously not sure why. Because this thing blows completely at anything except short range engagements and sometimes thanks again to bloom, medium range engagements. It takes 7 shots to the head, 9 to the chest, 11 to the crouch and 10 to the legs to kill. Because cone of fire widens completely at around 6 shots, it makes zero sense at any range to time shots except for extremely long range when a player isn’t even shooting back, but at that point why even engage because it’s still going to take 7 shots which gives them ample time to remove from my line of sight so again, zoom in completely and spray and pray and hope bloom is on your side. If the Pistol’s bloom was a little less and reset was quicker, the pistol would feel much snappier and capable against another weapon (when you aren’t able to get a PW or BR on map) at close-med range, long range would still get out gunned unless they have terrible aim which I think is decent since BR / AR should win out at longer engagements unless the pistol was timed perfectly and had quicker reset to get off the 7 headshots needed to kill. Overall I’ve seen two types of players in arena, those who use the AR fullspray and people using only Pistol and letting bloom dictate the fight rather then aim / nade placement / movement outplay skill. Personal opinion is the Halo 5 pistol was the best Halo pistol ever made, let’s not talk about the magnum cause that thing was OP and definitely wouldn’t enjoy something that powerful with infinite’s player movement.
BR: 3 body shots 1 headshot, same 4 shots to head, 6 to body to kill. The BR is nice, but compared to any other Halo, this thing blows. This isn’t going to make even casual players enjoy much going for weapons on the map because any casual gamer is not going to have good enough aim to hit 4 headshots back to back while the ARs TTK at full spray will out gun the BR currently. Longest TTK for a BR in halo ever. The bloom on it feels like other Halo’s could be wrong but as far as the actually shooting of the weapon it feels great, I love the recoil, love the audio, love the look, but the TTK is an abomination to the infamous Halo BR. Would love to see it be changed to allow 3 headshots, keep 3 body 1 head, 5 body shots to kill (not sure how that translates to damage output or how that affects effective damage range) but right now at all ranges, 4 headshots makes the BR super unrewarding especially for how much cover there is on these maps.
VK78 Commando:
7 headshots, 6 body shots 1 headshot, 10 body shots. This thing is a BEAM, it’s like the DMR on crack. short-long range slaying machine. Fast rate of fire, small cone of fire. Absolute hands down best weapon in the game. I have consistently outgunned a BR at every range in arena so far. Please don’t change this thing, cause it’s all I’m going to pick up and use 
Pulse Carbine:
2 3 round burst headshot to kill. I didn’t play the first tech flight, and I read it was made easier to hit people with it, which is surprising because in practice when an enemy is moving / jumping this thing barely has any magnetism to it and is definitely not something I’ll be using. TTK with it is super slow because rate of fire is slow and amount of body shots it takes you’ll be outgunned by any of the above weapons immediately. Would love to see how it feels after magnetism of the 3 round burst is increased and possibly a quicker rate of fire, could put it in a place where it can compete against a BR or the Commando.
Bulldog:
3 body shots at close range, 2 headshots at close range, full clip at medium range to body 4-5 depending on bloom spread at medium range, long range just don’t even use it. This isn’t a shotgun. If I can’t 1 shot headshot someone at close range, it’s a tickle gun that is only going to get me killed directly after using it. No way you’ll be taking on more than 1 person with it in a tight fight. Somebody really needs to look into how a shotgun should do damage. I will say the recoil and rate of fire on it are great. If you want to keep the damage the same to make it more casual friendly then you’re going to need to up rate of fire or decrease spread so medium range fights when landing headshots are more effective.
Nades:
The regular grenade is having some weird inconsistencies with trajectory after being thrown. I can throw a nade and sometimes will bounce exactly to where I think, in other places it bounces completely unexpected and lands way shorter then it should. I think this has more to do with the map terrain than it does with the grenade itself and how the grenade interacts with the objects with collision detection. Sticky nades, love them as always. Spike nade, eh it’s alright only throws out a bit of damage since only 1 projectile will usually only hit an enemy out of the 7-8 I appears to do. Electric nade (not sure what it’s called), pretty cool nade I like the armor removing power it has.
Not going to cover power weapons because I’ve only used sniper and rockets and those are great
Player movement:
Sprinting and sliding feel sluggish. I can hit sprint and it takes time for the sprint to even engage, almost feels like there is a delay. Same thing with the slide. I’ll be sprinting hit the slide keybind and it takes a full second before my player even starts to slide. I’d expect to immediately enter a slide and be able to immediately come out of a slide. Sorry to make comparison, but H5 and CoD are good examples