Dickinson's work is known for its individualistic style, in that she capitalizes random words (presumably to add emphasis) and prefers dashes over commas and semicolons, a choice which is slightly more emphatic and eye-catching than the usual punctuation.
Beyond such general observations, this is a unique poem in that Death is a civil being, nothing to be feared. Death is commonly personified in poetry, but the fact that he is a gentleman, he takes his time ("he knew no haste"), and what she finds when Death takes her into her carriage is pleasant instead of frightening is unique.
Her poem almost makes us look forward to death. And she's still riding in the carriage at the end of the poem, presumably enjoying the scenery, as well as Death's "civil" company: "Since then – ‘tis Centuries – and yet / Feels shorter than the Day," from the time she realized that this was to be her eternity.