At first "Remembrance" sounds like your typical elegy: cold and dead in that dreary grave. But when the speaker starts getting into the whole memory bit and her anxieties about forgetting to love, we suddenly feel as if we're hearing a different perspective on death and loss.
In other words, this elegy sounds a bit more contemplative and intellectual than most. It's as if we're in a slightly more cerebral part of the speaker's grieving process that is less about tears and more about the human mind with "Time's all severing wave."
The ending rhetorical questions that we see in the first, second, and eighth stanzas really set the intellectual mood and sound, while the wavy iambic pentameter keeps it all sounding rhythmic. Plus, with all of those metrical deviations, which add to the speaker's lingering mood and thoughts (1-2), we really sense the authenticity behind her emotions and the way she keeps jumping around between sorrow, question, and later consolation. The sound of the meter really brings those emotions to life, especially when the speaker gets to the part where she's feeling stronger and those syllables start sounding shorter and more emphatic: "Then did I check the tears of useless passion."
Likewise, the anaphora we see in lines 17-20 really drives home the speaker's love, which comes second to none. By repeating phrases like "All my life's bliss," the speaker sounds as if she's really driving home her conviction that although she might forget, there's still no doubting her love and faithfulness to the one she lost. Alliteration also plays a key role in accenting her conviction, like the kind we see in lines 21-22, that uses that D sound: "Despair was powerless to destroy." It's as if the speaker sounds like she's determined to keep her despair in check by pummeling it with lots of D's.
All in all, this elegy sounds well balanced between the essentials: meter, rhyme, anaphora, and alliteration. Each device is carefully used in a way that best serves the speaker's tone and mood by creating complementary sounds. So whether we're floating over the mountains or being washed away by the "world's tide," we always have the sound of the words to remind us of where we are and how the speaker's feeling.