Just because a game has 4 CDs doesn't mean it's gonna play like it's 4 CDs!
D2 has got to be one of the more tedious games I have ever played. There is a constant need to go back and forth throughout sections of the world. During this time, there will be the incredible cut-scenes as mentioned above. However, after you get past the glorification, they get annoying! Trust me, they are waaaaaay too long and boring, for the most part.
One feature I liked was the need to hunt for food (which increases your Hit Points). Pull out your rifle and earn some meat. Also while exploring outside, D2 offers pop-up battles that will earn you experience points and level ups. RPG fans may like this feature, but if you aren't used to it, it is highly annoying. When you come to the fight scenes, you will notice that you are actually at the same spot that you encountered the enemy. This is a great addition when compared to the mysterious background changes present in most RPG games. The actual fighting seems more like an arcade gun-shooter.
Honestly I don't know what I would classify D2 as. It has elements from different genres including RPG, Action/Adventure, Shooter, and probably a bit of Interactive Cinematics. No matter what you call it, however, D2 just isn't that enjoyable.
The game does switch between 3rd and 1st person modes to break up some of the monotony. While indoors, just as the PlayStation game 'D' also was, you will be restricted to certain sections of the house while in 1st person mode (fighting scenes are also looking through the eyes of the lead character). However, while roaming outside you will be in 3rd person mode, giving you free range of movement (down the paths, at least). It is here where you will gain experience.