I do not think that the Celtic otherworld has that type of extreme dichotomy that you find in the Judeo-Christian tradition.
Nor do I believe that it depends on your view of it.
I'm not an expert, but considering what I've read, it just seems to be a place, or places that various heroes from myth
have found themselves in. What they find there depends on what is relevant to the story.
For example, when Cuchulainn was asked to visit the otherworld in order to help a fairy woman
in a battle, he not only went over the sea to reach it, but he helped her win the battle.
This does not mean that the otherworld is a place of warfare, it just means that warfare can be a feature of it
sometimes, depending on the story.
A place for the dead is also one of its features. Or, according to one author, it is a feature of one
of the many otherworlds.
There is a small island off the coast of Ireland called the place of Donn.
He is a god of the dead and his island is thought to be where the dead go. Or at least according to some traditions.
The dead lived a life I believe somewhat like this one. One writer I remember saying that it is a happier place.
But you do not remain there. There is a constant exchage of souls between this world and the otherworld.
If somebody dies in this world, then that person is reborn in the otherworld.
One who dies in the otherworld, is then reborn in this one.
So to the Celtic minset, it is apparent that no one really dies in the first place; you go off to the otherworld and you
can die there too.
A little confusing, but that is the dreamy Celts for you.