Two words: Lady. Ligeia. Say it out loud. You can't help but deliver it, as Hamlet says, "trippingly on the tongue." That's a big part of Poe's style, even if it does sound a little ridiculous. (If you read the "What's Up With the Title?" section, you know that Poe went so far as to make up names like Ligeia because he simply liked the way they sounded.) In this case, the phrase is nice because of a little thing called "alliteration." That's a big word to describe when two or more words that are close together begin with the same sound.
Poe really liked this kind of stuff, alliteration and all sorts of other little linguistic tricks. Just look at the last line: "'Here then, at least,' I shrieked aloud, 'can I never be mistaken – these are the full, and the black, and the wild eyes – of my lost love – of the lady – of the LADY LIGEIA'" (29). The sentence is chock full of alliteration: lost, love, lady, LADY, and LIGEIA.
Poe repeats other stuff, too: that long list of adjectives connected by "and" – "the full, and the black, and the wild eyes." Each "and" is like a rap on the door: you can't help but pay attention. The same thing goes for all those "of the" phrases inserted at the end… but let's not get carried away. You can find this stuff all throughout Ligeia; Poe uses tricks like these to emphasize important things, in the same way you might use italics – which, by the Poe uses, too – to single out a word.
Now, we'd be letting you down if we didn't address some bigger stylistic choices, too: namely, that poem stuck right in the middle of the story and that quote that keeps popping up all over the place. These are some bold moves, and they demonstrate just how good Poe was with the whole word thing. Heck, he manages to pass off his own writing as something concocted by some English dude from the sixteenth century. And believe us, if we didn't have any help figuring that out, we needed help figuring out it was made up, too.