Here is the sonnet:
My mistress' eyes are nothing like the sun;
Coral is far more red than her lips' red;
If snow be white, why then her breasts are dun;
If hairs be wires, black wires grow on her head.
I have seen roses damask'd, red and white,
But no such roses see I in her cheeks;
And in some perfumes is there more delight
Than in the breath that from my mistress reeks.
I love to hear her speak, yet well I know
That music hath a far more pleasing sound;
I grant I never saw a goddess go;
My mistress, when she walks, treads on the ground:
And yet, by heaven, I think my love as rare
As any she belied with false compare
This sonnet is a parody of the traditional Elizabethan love sonnet. It seems like the author is criticizing his love more than praising her. He lists the many things that do NOT describe his love. Many of these things are used in traditional sonnets to describe one's love - voice like music, cheeks like roses, golden hair, etc. This man's love, however, is none of these things, and yet he loves her anyway. He does not need to compare her to false things.
Here are some poetic devices. Lots of similes and metaphors:
1. Simile - eyes are nothing like the sun (this is a negative simile, he says her eyes are not like the sun).
2. Metaphor - comparing her lips to coral (another negative - he says her lips are not red like coral)
3. Metaphor - comparing her voice to music (it is NOT like music)
Now, see if you can give it a try. What other comparisons does he make? Remember, they are mostly negative comparisons!
Read about Shakespeare's sonnets here on enotes.