My Mistress' eyes
Reading the title the reader can see that "my mistress" is an alliteration.
Considering the lay out you can understand that it is an Elizabethan-Shakespearian sonnet because it is composed by three quatrains and a rhyming couplet.
The speaking voice makes a comparisom between the mistress’ body and elements taken from nature, which result better than the woman: Shakespeare turns upside-down the curtly convention.
The poet loves his mistress even if she does not conform with the traditional beauty of the time. He wants to revalutate the human aspects.