Interpreting a Shakespearean Sonnet?

[Jessie's Girl]

Here is the sonnet:

Let me not to the marriage of true minds
Admit impediments. Love is not love
Which alters when it alteration finds,
Or bends with the remover to remove.
O, no! it is an ever-fixed mark,
That looks on tempests and is never shaken;
It is the star to every wandering bark,
Whose worth's unknown, although his height betaken.
Love's not Time's fool, though rosy lips and cheeks
Within his bending sickle's compass come;
Love alters not with his bref hours and weeks,
But bears it out even to the edge of doom.
If this be error, and upon me proved, I never writ, nor no man ever loved.

What is the argument?
Rhetorical Strategies/Terms?
Figurative Language?
Diction?
Syntax?
Rhyme Scheme?

Thanks!