I think I figured out a way to get past the graphical quality issues, temporarily, or just until you quit Brink. Can't say for pop-in textures. I also adjusted the sharpness on my tv to 100% to get rid of the "bacon smear". Anti-alias will look more noticable though.

I sometimes 'try' to multi-task by getting my homework done and playing a few matches of Brink on the side. Anyways, I leave the game on the Security menu (Love the music) and do homework for an hour or 2.
I went back into the game and landed on container city. In a few minutes, I saw and tested the quality of the place. The rails had much less blocks (anti-something), the textures loaded faster, and the whole map looked really good!
It carried on to other matches also, Aquareum, Transit.
I exited to play Assasin's Creed with some friends and then came back. I checked if they were still good... it looked like crap. I did something else in the meantime on my pc as I left the game at the menu. This time, I entered Resort, and the Security Wall. Looked perfect despite the small blocks that looked even less.

Long story short: Plan ahead. Leave Brink on the menu for an hour, then enter and check it out.

Obviously you don't want to burn your Xbox so just take precautions, I would think the best time to check to see if it worked is when the screen goes dark because of the controller automaticaly turning off. (Whenever that is) I'm probably over-exaggerating the time.

Details:

. Time and patience

. Xbox 360

. Installed to HDD

. Occupied