Hats off to Dickinson for the way this poem sounds. All those technical things we talked about in "Form and Meter" (meter, rhyme, anaphora, the dashes) really make for subtly-woven sound patterns. Take a look at the repeating rhymes again. Not only does the rhyme tie the poem together, but it draws attention to some very important words in the poem, "Immortality" and "Eternity."
None of the sounds are super loud or noticeable. This is not your neighbor at the drum set. It's almost as if Dickinson has done all of this behind our backs, so if you don't pay attention, you might not even realize it's there. The more attractive the poem sounds, the more you're going to want to read and pay attention. The meter, which is so sneakily undulating (think low-rolling hills), is lulling and attractive. You can almost imagine this poem set to the even sound of the horses' clomping hooves; the real conversation is going on between the speaker and Death in the carriage, but the hooves are always in the background. Very cool stuff.