DS2 is, imo, the most melancholy of the bunch. It's less about traversing and trying to revive a dead world, and more about the effect of the Hollowing on humans. Far more personal in that regard. Lucatiel is a great example of that process of degradation, while Vendrick gives you that "before using meth" and "after using meth" effect.
Vendrick destroyed the giants (not without the help of our time traveling chosen undead, of course), and sought the crowns to battle the hollowing, but (probably) failed because Nashandra found him. He's no pussy, but you still see the husk of a once great man.
What's most interesting is Vendrick actually suggests 'hollow' is the true nature of man when you obtain 2, and then 3 DLC crowns.
"Shadow is not cast, but born of fire.
And, the brighter the flame, the deeper the shadow.
Inherit fire, and harness the Dark.
Such is the calling of a true leader…"
"One day, fire will fade, and Dark will become a curse.
Men will be free from death, left to wander eternally.
Dark will again be ours, and in our true shape…
We can bury the false legends of yore… Only…
Is this our only choice?
Seeker of fire, coveter of the throne.
Seek strength.
The rest will follow…"
Sounds to me like Vendrick (and his brother, Aldia) knows we're fucked, and doomed to be Hollow no matter what happens, but wanted to fight the good fight anyway. DS1 allows you to 'sin,' and light the fire at the cost of your own life, like Gwyn. Before the DLC, DS2 allows you to take the throne and control the giants...while facing the inevitability of hollowing. In Scholar, you obtain all 3 Crowns and fight off Hollowing, but only for 1 person. Unless you can carry the flame within you to preserve humanity, you're left both alone and aware. Pretty damn depressing.
Oh, and the Shaded Woods into Tseldora is all animals, and demi-humans. Most likely a dumping ground for Aldia's failed experiments towards obtaining immortality or whatever. Pretty sadistic shit.