Reposting from the Bloodborne Press Preview thread. The GAFfer whose question I answered found it helpful.
I'm one of those people that never played a souls game and decided I might give Bloodborne a shot. What do you think it is that people will not expect?
What I don't like about many modern games is that they hold your hand. There's always a big arrow on the screen telling you to head this way for 300 feet or someone calling you on a radio and telling you what to do. The combat in many games was also not very difficult (mash X to win kinda easy). A lot of people play these kinds of games and enjoy them, but the Souls games are not like those games.
A big thing about the Souls games is that it doesn't hold your hand. There were always basic tutorials in the beginning of the game, but many mechanics of the game are not explained (for example, in Dark Souls, you can roll faster if your equip weight was <50% of the max equip weight, but the game never tells you this outright). There are no waypoint markers, no guy on a radio giving you directions. The Souls games required people to have a lot of patience: read every item description, read up on what every stat in the menu means, talk to NPCs multiple times for hints on where to go/lore about the game world. In Dark Souls, right from the proper beginning of the game (after the tutorial), you have a few different ways to go. Some of those paths lead to areas that you should visit later, but many people learned that the hard way. There is an NPC who will give you a hint of where you should go, but you'd need to actually talk and listen to him.
Combat in Souls games were not button mashy. You can't just mash R1 and expect to kill things easily. Much like Monster Hunter, each attack has an animation that cannot be canceled. When you press R1, you will be locked into the attack until its animation is completed. It is definitely more deliberate and slower paced than say, DMC or Revengeance. And even the first enemy you come across can fuck your shit up. You've got to respect every enemy in the game and try not to rush things. Watching an old Game Informers video Dan Ryckert play Dark Souls for the first time, he made an interesting observation; The combat in Dark Souls is like Punch Out: enemies have patterns that you'll have to learn, you can only safely attack at certain moments, a specific enemy attack/pattern/animation is a tell and you should roll in a certain direction to avoid it. Bloodborne combat being faster paced than previous Souls games doesn't mean it will play more like DMC or Revengeance. Attack animations will still be there.
And a big thing in the Souls games is death. Everyone dies all the time to enemies, and the environment. You'll lose your souls (which is your XP and currency combined). People might become very frustrated and lose patience when they hit a wall.
I can see a lot of people being interested in Bloodborne because many on GAF are super hyped for it (including me!). If you can be patient, give every enemy the respect they deserve, and pay attention to things, then you'll do fine. If not, then you might become frustrated and not have fun with the game. The Souls games are difficult, but not as difficult as you might think. Rather, they are games where you have to give your full attention.
Edit- If you've never played the Souls games and plan to not play any of them before Bloodborne, then check out a video or two on YouTube or Giant Bomb to get a feel of what Souls games are like.