Link to ign article here: http://www.ign.com/articles/2018/05/03/worlds-first-look-at-red-dead-redemption-2
But there is also a summary found on reddit I'll paste in case you don't want to follow the link:
Gang interaction is a big deal, and taking care of your gang's camp matters.
As Dutch’s right-hand man, Arthur plays an important role in the upkeep of the gang, not just in terms of supplies but also the morale of the gang. If food and resources are aplenty then spirits will be high, which is reflected in the mood of the camp. People will be singing and dancing, and you’ll be greeted with cheer. But if the food supply runs low, you’ll quickly know about it – people will mutter angrily about where the next meal is coming from. As a senior member of the gang, many will look to Arthur to provide, through hunting or buying supplies, and he’ll be rewarded for doing so. But thankfully the responsibility doesn’t fall entirely on your shoulders – Rockstar is keen to emphasise the camp will continue regardless of your input and is spending a lot of time balancing Arthur’s responsibilities with having fun.
Your gang will come to you when supplies run low, and it's up to you to decide to help or not. This comes through ambient dialogue, and doesn't trigger cutscenes. Apparently there's a lot of interactions like this.
Rockstar is trying to blur the lines between what’s a story mission and what’s a side quest, instead presenting them all as opportunities given to Arthur. Many are contextual too, dependent on the time of day, where you are and who you’re with.
Arthur has a variety of ways to interact with people around him, who will react differently based on their personalities.
When Arthur exits the camp and rides his horse along the dirt track, he’ll soon meet other people. Much like real life, they’re a mixed bunch; some are pleasant and polite, others are less welcoming. You have complete control over how Arthur acts in the world, thanks to a sophisticated interaction system represented by a number of choices displayed in the bottom right of the screen, such as Greet or Antagonise. These dynamically change depending on a number of factors, including where you are, who you’re talking to, choices you’ve made previously in the interaction and so on, and even though most of the HUD was switched off for the demo it was still obvious how much freedom the player is given.
There are other factors that impact the response you receive too. A farmer didn’t take too kindly to Arthur riding close to his land, telling him to move on in no uncertain terms. Likewise, a lone traveller resting against a fallen tree trunk is similarly wary when you trot past at dusk.
They describe a situation where Arthur attempts to burglarize a fisherman's camp as he's distracted with his fishing. However, the fisherman has a dog who barks at Arthur and alerts the fisherman who attempts to chase him away: "but he’s no match for the outlaw, who tells him to turn around and run. He doesn’t, so Arthur tries a more forceful approach, pushing him to the ground. It works and the fisherman scrambles to his feet and flees."
Horses have been improved in a number of big ways.
Firstly, Rockstar wants you to think of your horse as a companion rather than a disposable mode of transport, and as such you’ll build up a bond with your mount the more time you spend with it, calming it when it’s agitated, grooming it and feeding it. If you have a strong bond with your horse it’ll be generally be less skittish and calmer in firefights, and more inclined to do as you want, while an untrained horse is more unpredictable.
Your horse will only come to your whistles if it's close enough to hear them, it also carries most of your supplies; including large weapons.
When you dismount, your horse stays where it is: yes, you can call it with a whistle, but that’ll only work if it’s nearby. Bearing in mind your horse now not only gets you from A to B, but also carries most of your supplies and larger weapons, you’ll always want to know where it is.
Hunting has also been improved, and seems to be far more in-depth.
With the string pulled tight, he whistles to draw the deer’s attention and fires, the arrow striking it in its leg. It cries out in pain and attempts to run, but the wound is deep and, after following a blood trail for a few seconds, Arthur finds the buck collapsed on the ground, still alive but kicking its legs and screeching in agony. Arthur draws his knife and finishes what he started, plunging the blade into the animal’s heart.
Small animals will feed the camp for a short amount of time, whereas large animals can provide for much longer.
After killing an animal, you must transport it.
But first, Arthur needs to get it back to Pearson, picking up his prey and throwing it over his shoulders. It’s heavy, and Arthur is noticeably debilitated while carrying such a beast. Thankfully his horse is just a whistle away, and strapping the kill on the back of his mount makes the return journey a more enjoyable ride.
However, a word of caution – dead animals decay over time and while small prey can be wrapped and stashed in your satchel to prolong their use, the carcass of a deer left in the scorching midday sun will soon turn. Ensuring the buck is returned to the camp cook as soon as possible is therefore a priority.
Animals can be sold to butchers, but the condition you bring them in matters.
The same applies if you’re looking to sell the animal to a nearby butcher – the better the condition of the meat, the greater your reward. Equally, an animal riddled with buckshot will attract less of a reward than a clean kill with a single arrow.
After this, they talk about a small bank heist mission, and the choices you're given in how to approach it. From instructing your gang on what kind of distraction to provide, and how to open the safes during the heist itself.
Dead-Eye is back, and features cinematic kills.
But it’s too late – the sheriff and his deputies are already on the scene. Karen now tries the lost little girl act, walking out of the bank saying it was all a terrible mistake. Seconds later she’s followed by Arthur, who kicks open the doors, Dead Eye at the ready.
From the demo Dead Eye looks much the same as in the last game; the screen turns sepia and the action slows, giving the player a few seconds to mark targets before shooting. The four lawmen hit the dirt in a hail of gunfire before Arthur turns his focus to the deputies firing from on top of buildings. Long-distance kills play out in slow motion, shown from a reverse angle so you can fully appreciate the kill
Your hat can be knocked off, and you either have to retrieve it, or buy a new one.
Just as Arthur is about to climb on his horse a bullet fizzes past his head, knocking his hat clean off. According to Rockstar it’s not a prescribed moment, just something that can happen, and if you lose your hat it won’t miraculously reappear in the next scene – you’ll have to go back and get it if you’re willing to risk the heat, or buy another when you get the chance