Based on what I've played so far, the map doesn't look very big at the moment but maybe it opens up more, or maybe it doesn't I can't really tell! It does appear that everything is open but I haven't done much exploring as the game is leading me a certain way in the initial stages to set up the story. One thing I will say though is that without a climbing mechanic it kind of makes the world feel even smaller. On one hand Vampyr looks like it should play like an Assassins Creed type game, with the combat etc but the movement is nothing like Assassins Creed, you don't have nearly the same kind of freedom. The character interactions play out like a cross between Witcher and a Sherlock Holmes type game, with lots of dialogue choices. Overall it's definitely a hybrid of RPG and action horror. I'm still getting to grips with it and the menus are a bit confusing initially.
With the NPC characters you have a table where they are listed after you've met them and there are various hints about their character and person that you need to find out. It's kind of weird but interesting, I just need to wrap my head round it a bit more.
I really like what I've played but I need to get into the meat of the game a bit more to be honest.
[Show spoiler]I've kind of done the intro stuff where you get bitten and then learn a few abilities like how to track blood trails etc. As you are a doctor, you get a job at the hospital which kind of serves as your base of operations. Last night I stopped playing after I got to the hospital which is still very early on in the game, so I haven't actually gotten stuck into the main story.
I just hope the world feels bigger as the story develops as like I said, the map doesn't look that big. Atmosphere is great though and the gameplay has a lot to it and I lot to learn with various abilities to level up etc. You can't save on the spot though which I'm used to with RPG's.