You don’t need to have played the first game, as it introduces the world and characters very well, but obviously like any series, you will pick up on some stuff if you’ve played the first. The story and characters though are some of the best I’ve ever seen (including Enslaved). The characters are so well-written and so believable (even some of the minor characters who are just plain rude or nasty) that the world feels real.
The combat is also very intelligent, and quite realistic as well. You have fast attacks and powerful attacks, but the majority of the combat, especially on the higher difficulty levels, requires you to block, dodge and counter-attack to make sure you don’t get hit. Even on the easiest level, if you try to fight without defending yourself, you will die very easily and quickly. However, if you haven’t played the first game, I’d advise against trying it on hard first time round, because you will NEED to use alchemy to survive.
The graphics are stunning, if your PC can handle it. The attention to detail in the environments is brilliant because the world looks and feels alive. In one dev diary video they even showed how for outdoors environments they consider stuff like where the sun falls, especially in forests, as to where they put plants and paths, and it shows.
However, it can be demanding on your PC. My gaming laptop has an Intel i5 2.66 Ghz (that boosts to 2.93), 4GB RAM and ATI HD545V (1GB VRAM), and it runs fine… so long as I don’t put the resolution higher than 1024 by 768. I think the problem is with my graphics card not being able to handle the extra work required for higher resolutions, rather than the game, but it’s just a bit odd. I can have basically all the options on or on high, so long as I don’t push the resolution. However, for people on here who are more likely to have proper desktop gaming rigs, you should easily be able to get the kind of graphics in the screenshots that The can posted.
TL; DR: don’t need to have played the first game but you might miss some references, believable story and characters, difficult but fair combat, stunning graphics if your rig can handle it.