"Reanimator" is one of the earlier uses of (I would argue) a good fictional trait fairly specific to HPL -- the exercise of Lovecraftian philosophy, by a Lovecraft character, ends in disaster. (Imagine an Ayn Rand novel in which the selfish, brilliant protagonist dies hated, miserable, impoverished, and alone. Or, to bring it down a notch, a Robert E. Howard story where the proud barbarian is tricked by the wily city folk and winds up exhibited in a zoo or pulling a manure cart for a plantation.) Herbert West, like Lovecraft, believes that life is purely chemical -- and demonstrates that belief, and inevitably loses not only his life (in gruesome fashion) but earlier, his scientific mind as well (replacing it with "mere morbid and ghoulish curiosity"). Lovecraft regularly kills his Mary Sues, often for the crime of believing what Lovecraft believes. Not always -- Randolph Carter survives where Charles Dexter Ward doesn't (although Joshi argues fairly convincingly that both those novels are conscious epilogues to previous Lovecraftian aesthetics) -- but more often than not.
Re-reading the story, I was struck again by the sheer awesomeness of Herbert West's tissue culture, "obtained from the nearly hatched eggs of an indescribable tropical reptile .... It was better than human material for maintaining life in organless fragments, and that was now my friend's chief activity. In a dark corner of the laboratory, over a queer incubating burner, he kept a large covered vat full of this reptilian cell-matter; which multiplied and grew puffily and hideously." I swear, if I ever came up with something that neat, I'd take the rest of the week off.
NEXT: "The Hound"