Issues that definitely, without a doubt, need fixing:
Hitting downed players
Horse audio is too quiet
Blocking thrusts with side blocks
Imprecise shield hitboxes
Poor body parts hitboxes
Issues that could very well be a matter of multiplayer latency:
Delay on release of attacks
Variable attack delay
Accelerated attacks
Issues that could be a matter of attempted multiplayer fairness balance that requires tweaks:
Defender stun & initiative
Very fast stun recovery
Shields durability is too high
Character height and hitbox size (but definitely needs fixing if not)
Switching weapons before and while getting hit
Issues that I've heard are being looked into:
Chamber blocking is non-functional
Cavalry movement and crushthrough
Issues that I take issue with:
Everything wrong with kicking: The complaint is twofold: One, that the foot doesn't come down faster when hitting an opponent. I'm not certain this is even the intended effect. Perhaps it is. My big issue is with the second complaint, however: The stun being too short to attack with short weapons. I feel this is the way it should be. The advantage of short weapons is their attack speed. If you can kick and attack with a short weapon, the enemy has pretty much no defense against you except offense. If they try to go toe-to-toe with you, your faster weapon will beat theirs the majority of the time. I feel that being unable to follow up on kicks with short weapon attacks is perfectly reasonable.
Stance affecting combo speed: The slight speed increases look natural to my eye when paired with the respective animations. Maybe it's not supposed to be this way, but it looks right to my eye.
Movement speed depending on stance: Likewise, this looks right to me. If you're swinging with your movement, you have no reason to slow down. If you're swinging across your body, however you need to twist your body, which means you'd consciously slow your lateral movement. It's the same as a quarterback throwing cross-body as opposed to throwing in the direction of their scramble when running. You don't need to slow overmuch if you're throwing in the direction you're running but you practically need to stop if you want to twist the other way and throw to the opposite side of the field.
Shields durability is too high: In addition to perhaps merely being a multiplayer balance facet that we won't see in singleplayer, I personally prefer it if shields are a little tougher. Realistically, a sword is not going to destroy a shield in 10-15 hits. Axes do much better work, and as it should be, it seems they make fairly quick work of shields ingame at the moment.
Just take a look at how this simple shield made out of friggin' plywood holds up to various weapons, standing stationary to be hit.
Height variable: As a multiplayer concern, I can completely understand this being a problem. Solution: Take the height slider out of multiplayer. As a general mechanic, however, height should absolutely have a tangible effect on combat, as it would in real life.
Imprecise cavalry swings: This one's tough. On the one hand, I see what's being said, but on the other, if many of those one-handed windups were placed where the video suggests they should be placed, they'd look incredibly unnatural. Joint tolerances have to be accounted for, but at the same time, surely you don't expect a cavalryman to swing his sword directly into his own leg.
Knocking players down as cavalry is too easy: Really, though? Stand in front of a horse running at the speeds shown in this video. Even horses without armor adding to their mass. See if you can keep standing as they run square into you. There are a couple of instances in here where I wouldn't mind seeing a stagger instead, but the horse keeps moving, and you're not going to stop it. Unless you sidestep, you're going down.
Attacking over your mount's head: That's on the player posting the issue. When you release an attack a split-second after shifting a loaded animation from the left to the right of your mount, no, I don't want your character doing a back-wrenching 45 degree twist in 0.25 seconds and releasing a perfectly aimed thrust. Be careful where you're pointing your spear, same as an actual lancer would have to be.
Downed horsemen, blocking and pivoting: To answer the poster's question, it's different because of momentum. If your horse suddenly gives way to the side, inertia doesn't give you an opportunity to raise a shield in a meaningful defense. If, on the other hand, your body weight is forward and your horse goes down in full stride, you being flung forward has no negative effect on your ability to raise your shield in front of you.
Camera position shift on knockdown: It gives knockdowns some added weight. Like your character, your view of the world has suddenly shifted in a somewhat disorienting way, and you need to quickly reacquire whatever you were looking at when you get up. I see no problem with this mechanic.
Partially drawn bow not incurring a speed penalty: Would raising a bow quarter-drawn negatively affect an archer's speed in real life? I don't see how it would. Therefore, it shouldn't have one in Bannerlord. The poster says "there's no reason to not use this mechanic", and that's how it should be. A mobile archer of reasonable skill should always be ready to fire another arrow. It does, however, have the slight downside of taking a split second longer to switch to a melee weapon, should one feel the need. Seems fitting to me.
Switching weapons before and while getting hit: Short of dropping the weapon you were holding and now having no weapon in hand, I don't see how else to handle this. It doesn't seem you should be rewarded for deciding to switch weapons at an inopportune moment in the heat of combat. If you tried to do what the video demonstrates in real life, you'd probably have your arm broken, which would at the very least mean you wouldn't be drawing that sword and shield.
Height does not affect reach: I don't have a huge problem with this simply because, at the differences shown, it's perfectly reasonable for two individuals to have the same reach. Height isn't a uniform calculation. Many people have an arm length beyond the norm, or vice versa. It's not at all impossible to find someone with four extra inches of leg length with no extra arm length. But height should, realistically, have an affect as this is the norm. Good news, though!
Tapping W on horseback: Heavens, our man Noudelle gets infuriated easily. (I appreciate his obsessive bugtesting work, though, doing it like a beta tester should!) Personally, I don't find this a problem. One shouldn't be able to walk his horse in close combat. Horses are living creatures with a sense of self-preservation, and they're highly unlikely to walk slowly this way or that when the noise of battle floods their ears and shiny sharp objects are swinging in their vicinity.
Automatic attack direction switching: I get his point, but I don't mind this one bit. I think it should be a toggle, though.
Insufficient evidence for judgment:
Leg hitboxes when mounted
Lack of animation for aiming up and down