When I read Death Note several years ago, I was very, very disappointed with its ending. So this self-righteous bastard, this mass killer, got Nothingness as his sentence? Not fair! Compared to that, Sartre's Existential Hell is, well, hell.
At first glance, it might seem that the other way around is true. My vanity, or my will to power, or whatever you want to call it, cringed from the idea that one day I would be no more, forgotten completely, my traces of existence wiped out by the passage of time. In contrast, Antoine Roquentin's plight in Nausea is "so vague, so metaphysical that I am ashamed of it."
But here's what I realized from reading Death Note: nothingness is only undesirable when seen from the perspective of existence. If there is such thing as non-existence, by the time you're at it (I know my statement is full of semantic contradictions, but please bear with me for the sake of argument) you won't even conscious anymore of your nothingness, your insignificance; there will be no pain, no happiness, no emotion, absolutely nothing. Plainly speaking, what's to fear about nothingness when you're not even aware of it? (Because, of course, in Nothingness, there's no such thing as awareness/consciousness/perception/soul.)
Now consider the horrors of existence. Roquentin obviously rejects the notion that this world is but a transit station, that the meaning of this life is derived from the eternal. Life is here and now, there is no before- and after-, and so, what's the point? We all are going to die in the end anyway. Why one finds himself here in the first place? It seems weird and futile and meaningless.
Even though some parts of Nausea felt dragging and boring, which is deliberate, I'm sure, because that's how life is, others hit me hard because they rang true. For example, the time Roquentin looked at his old photos and mused about the (un)truthfulness of memories--"As for the square in Meknes, where I used to go every day . . . I do not see it any more. All that remains is the vague feeling that it was charming . . . . I can search the past in vain, I can only find these scraps of images and I am not sure what thy represent, whether they are memories or just fiction." Or the burden of thoughts that refused to be silenced--"Thoughts . . . stretch out and there's no end to them . . . . Then there are words, inside the thoughts . . . a sketchy sentence which constantly returns: . . . 'Smoke . . . not to think . . . don't want to think ... I think I don't want to think. I mustn't think that I don't want to think. Because that's still a thought.'"
I exist, and that's all.
Note: As far as I know--and I'm not very knowledgable to say the least--the only religion that explicitly states that non-existence is bad is the old Egyptian religion. Even then, I'm guessing the idea of Ammit the crocodile-lion-hippopotamus demon hybrid devouring your heart is more frightening than non-existence itself. Anyone care to enlighten me more about the topic?