When a colossal monster attacks New York City, a partygoer and his friends must rescue his girlfriend in the middle of the chaos while documenting the events. — Cloverfield (2008)

Gemini Silver,

This is an interesting example to discuss.  At 23 words,  your logline is succinct and does the job of laying out the basic elements of the plot.

However.

The unique element about the movie is not so much the plot nor the monster. Rather, I’m guessing what sold movie tickets was how the script was shot,  the cinematic technique used  in the filming  It’s all shot from POV of the protagonist’s hand-held video camera. (Like “The Blair Witch Project”, which made a mountain of money for the directors/writers.)

If this were a logline for an unproduced spec script by an unknown writer without any representation or contacts in the business, I doubt if it would get the script read.  Why?  Principally, IMHO, because the logline has no story hook, nothing  truly unique, nothing that stands out from the glut of monster movies with fair damsels in distress.

I am inclined to believe that the script got read because the writer had already established himself in the business.  He wrote and sold 15 scripts for TV series over a four year span.(according to IMDB).  He had an agent to field this script. He had contacts and friends in the industry whom he could  — and no doubt did -pitch the story to.   That, IMHO, is how he got the script sold and made.

I agree with dpg, I think your logline works, however, I do wonder if you could add the part where they document the events.