[quote]Is that similar to upvote/downvote on reddit?[/quote] Yes, it affects whether the thread is trending or not. [quote]Are the up and down arrows available on the destiny companion app[/quote] Upvote is disguised as a little star when you tap a comment or post, and you can downvote OPs by tapping their post, tapping on the three dots, and selecting "dislike." [quote]What are the qualifications for highest-rated?[/quote] A very high volume of likes, and I believe comments being liked in the post also affects this. [quote]What are the consequences for high or low scores?[/quote] If it's a high scoring post, it hits trending and highest rated. If it's low scoring, you'll only find it in latest. Bungie is still working on the system quite a bit, and I don't work for them, so I don't know all the details. Hope I helped though :)