Playful, flippant, and to-the-point, our speaker sure knows how to pack wallop. After all, you've got to combine a whole lot of qualities if you're going to manage to thumb your nose at metrical tradition, literary tradition, and, well, tradition in general.
Our speaker basically writes a poem about her awesomeness (as a poet, a lover, or just a liver)—and she manages to make us think she's funny while she's doing it. And what's more, we sorta love her even when she's bragging (after all, she does call her own light "lovely"). Perhaps that's because the speaker is so clearly aware of the costs of greatness: if you play hard, you burn out.
Come to think of it, though, we don't know all that much about her (it could even be a him for that matter). If we were to imagine an I.D. card, it would be pretty much a big fat blank. Name? No idea. Location? None. D.O.B.? Beats us.
What we do know, though, is that our speaker is audacious, audacious enough to introduce herself by proclaiming that she might not last long, but she's going to go out with a bang. And she's witty enough to do it in a sing-song like tone, with simple words that almost sound like a schoolyard song. (Iambic verse tends to sound sing-songy, if only because the pairing of unstressed and stressed syllables sounds, well, like a rocking motion.)
We'd like to pause for a moment to introduce little bit of Shmoop gossip: strangely, this proclamation ended up mirroring Millay's own life: a quick, fiery burst of literary production, a series of torrid love affairs, and an all-too-early death. Perhaps that's why many critics associate the speaker with Millay herself.
Regardless, our speaker seems to go out of her way not to identify herself, despite introducing the poem with a strong personal possessive ("my"). There's not even any special technical vocabulary to clue us in to her career or her relationship with either her friends or her foes. It's a strange anonymity for someone making a claim to greatness—which is perhaps what makes our speaker so very appealing.