Anyone that considers themselves a fan of the superhero genre should watch this show. I'd say the graphic violence is the largest obstacle as a viewer; if you can get over that, get ready for a show with equal parts quality writing, an intricate universe, awesome animation, and a lingering sense of suspense.
The contrast between a naive, borderline satirical tone and the brutal realities of life as a superhero is the most profound aspect of this show, to me anyway. It's been done before, sure; the execution and absolute proficiency of that central concept, however, is what sets this show apart from its contemporaries.