The theme statement in your post is exactly the point that Shakespeare is making in this sonnet. He is describing his beloved in some not so flattering terms. Frankly, the poem is kind of insulting on the surface. He says that his beloved's eyes are not bright, that her lips are not red, that her skin isn't light, that her hair is wiry, that her cheeks are pale, that her breath is bad, that her voice isn't melodious, and that she doesn't walk with much grace. With all that said though, the point of the poem is comes in the concluding couplet. Here is says that his love (beloved) is more rare and special than other women. Shakespeare is actually kind of making fun of all the rather cliched comparisons that men use when describing a woman's beauty. They aren't really true, but exaggerations, and this speaker would rather just tell the truth and still state that he is love is special and rare without all the false comparisons that really mean nothing.