Doesn't look at all realistic to me, but I guess it's different for people (e.g., you) that have never seen someone die.
True. In fact it looks very unrealistic, with highly exaggerated amounts of blood. The point is that the visual / audio effects attempt to create an impression of extreme gore, bloodshed, and agony, which the player obviously takes pleasure in inflicting. Again, my point is best expressed by asking: "Why you would derive pleasure from this?" I'm not implying that your reasons for enjoying this are good or bad, just that answering this question would put a lot of confusion to an end.
Please prove me wrong, but I have a feeling that this question isn't being answered because many of you are ashamed to answer it honestly.