Why do you love Letterboxd?

For whatever reason, although I am big movie person and watch a ton of movies, I never found a reason to download letterboxd. I get that you can rate your movies and see what your friends watched, but is there anymore beyond that? I feel like I can come on reddit and chat about it or get more out of a youtube deep dive. My best friend on the other hand loves letterboxd, and I am thinking maybe I'll make one to make them happy about me joining, but still want to know what the communities favorite features are.

Also - for rating nomenclature, there is a 1 to 5 rating along with a star? My friend always mentions it, but I don't know what it necessarily means and why you'd star or not star, especially if it's a mid-rating.

Appreciate any insights!