The Flowers of Evil is and always has been a notorious book. The easiest way to describe it is as transgressive poetry. Baudelaire is in no way revolutionary or even innovative as to form. He uses traditional poetical forms and his poems are complete with classical illusions. Nor is his subject matter particularly novel. Baudelaire did not invent writing poetry about the dregs of humanity, about death or human heartlessness. What is novel about the poetry is the unrelenting ironic stance. Baudelaire takes traditional poetry and inverts it. His most notorious poem, and probably his best, The Carcass is a love poem which is similar in form to Shakespeare's poem Shall I Compare thee to a Summer's Day. In each poem the poet compares his beloved to something and claims immortality for his beloved through the poem's comparison. In Shakespeare's poem the comparison is to a beautiful summer's day and in Baudelaire's it is to a rotting human carcass. That's Baudelaire in a nutshell.
Pretty much all of The Flowers of Evil concerns these kind of reversals. For instance, it even has hymns to Satan. Baudelaire is like a modern ironic hipster, spurting out ironic hipster witty reversals. Not surprisingly that can be quite shallow at times and Baudelaire often reads as if he is being shocking to be shocking and has no greater purpose. However, having said that there is absolutely talent here. Many of the poems are very well done, some of them even have a serious point as well. Baudelaire is not as deep as he thinks he is, just as most cynical hipsters are not as deep as they think they are, but almost despite himself, many of them poems are very good. That makes for a very uneven collection, and I also found that a little Baudelaire goes a long way. I read the collection a few poems at a time over the course of months. Anyway, Baudelaire is a poet who is good almost despite himself and a poet who prefigured some of the best and worst literature that was to follow him.