I guess someone other than Alicorn should also answer this.
It's competently written and pretty enjoyable, but not as much as Methods of Rationality.
I haven't read so much as a word from the novels nor watched so much as a trailer from any of the movies, and had successfully avoided learning anything about the contents except the names of the two protagonists and that it's a paranormal romance with sparkling vampires and werewolves (I despise paranormal romances and vampire fiction in general). I had no trouble at all following along, and the world managed to not come across as exceptionally stupid, contrary to the very vague second hand impressions I had, despite apparently canon compliant world building. It starts a bit slow but is pretty engaging despite the long introspective monologues, which must be difficult to pull off. It's much more down to earth than Methods of Rationality, nowhere near as crazy, doesn't contain as much humor and is much more even in tone.
In the vein of the Harry Potter and the Methods of Rationality discussion threads this is the place to discuss anything relating to Alicorn's Twilight fanfic Luminosity. The fanfic is also archived on Alicorn's own website <strike>(warning: white text on black background)</strike>.
Previous discussion is hidden so deeply within the first Methods of Rationality thread that it's difficult to find even if you already know it exists.
Similar to how Eliezer's fanfic popularizes material from his sequences Alicorn is using the insights from her Luminosity sequence.
Spoilers for the fanfic itself as well as the original novels need and should not be hidden, but spoiler protection still applies for any other works of fiction, except for Harry Potter and the Methods of Rationality chapters more than a week old so we can freely discuss similarities and differences.
EDIT: Post-ginormous-spoiler discussion should go to the second thread. (If you have any doubt on whether you have reached the spoiler in question you have not.)