What is a critical view of "The Slave's Dream" by Henry Wadsworth Longfellow?

Henry Wadsworth Longfellow's heartfelt poem "The Slave's
Dream" is structured as eight sestet stanzas in alternating lines of iambic tetrameter
and iambic trimeter with a rhyme scheme of a b c b d b  etc., varying the Italian sestet
rhyme scheme of a b c a b c, in which the trimeter lines correspond with the b-position
rhymes. The poetic speaker, who is not the poet himself, is narrating the slave's dream
and experience in this dream vision poem.

The poem starts
out by positioning the slave laying down beside his work, his tool in his hand, with the
"mist and shadow of sleep" about him as he dreams of his "Native Land" where he is a
beloved king, with loving wife and children, who rides on a fast horse decked in gold.
The dream vision follows the king on a fast ride past landmarks of his beloved land
where he smiles at lions, hyenas and the desert blast. The ending reveals that the slave
is beyond the pain of the slave "driver's whip," beyond the "burning heat of day," for
"Death" has "illuminated" his sleep and set his soul
free.

Some of the poetic techniques (one of the two
categories of poetic devices) Longfellow uses are metaphor, simile, personification, and
irony. An example of metaphor is "mist and shadow of sleep." An example of simile is
"like a glorious roll of drums." An example of personification is "Blast of the Desert
cried aloud." An example of irony is "Death had illuminated the Land of Sleep." This is
creatively ironic because death is associated in poetic convention with darkness and
chains of despair, yet Longfellow sees that for the slave death is an illumination of
light and a freedom of release; these are the opposite of the poetic
convention.