To start off with just the basics:
-Your targeting reticule is a tiny white dot in the middle of the screen. Why the fuck would they do that, idk.
-You get slow-mo mode, which is pretty useful(basically you can take out anyone near you), but it recharges by time. No matter how many people you kill, it will not increase the things regen rate.
Now for Single Player.
When i heard this game was in the wild west, i was overjoyed, i thought that rockstar would finally make a game where i could be an outlaw badass, rob banks, and take over trains.
this game is probably the most linear free-roam game i've ever seen. First of all, you can't be an outlaw. Anyone you kill, no matter if anyone see's you, increases your bounty, which is pretty much impossible to pay off. Its basically 50-100 bucks per kill, and you get about 4-10 bucks at most from looting. You can't decrease it either. The only real way to get rid of it is to get a pardon note, which is plain luck of the loot.
You spend about the first 2-3 hours of gameplay being a bitch. You help some woman herd cattle, horses, and drive her places. Its fucking gay. Then you help out the sherrif, which i'd like except that killing outlaws doesn't raise your honor level.
1 civilian kill=50-100 negative
1 mission that can take up to 30 minutes= 100-200 honor positive.
Gee i wonder which one is going to happen more, especially with the horse kills you'll get because if you touch someone with your horse they're dead.
Respawn killing, nuff said. You spawn directly next to your killer about 90% of the time.