I have been playing Mirror's Edge Catalyst in the closed beta that started yesterday and am happy to report that the game runs well at 21:9. This was expected since it is a game build on the frostbite engine. Pretty much the same graphical settings as bf4, but a little less options. Maybe because it is still in beta or maybe it will be the same on release. The game has a much needed fov slider, but it isn't showing the exact values. Ingame cutscenes are rendered at 21:9 without showing any pop in or other artifacts associated with a wider then 16:9 aspect ratio. The pre rendered cutscenes are 16:9 with white bars... yes you heard it right, not black but white bars. The game looks beautiful and running it at 2560x1080 at ultra the performance is good for pre-release build (100-150 fps with occasional dips to 70-80).
EDIT: The hud elements are correctly displayed on the sides of the screen. I saw a maximum usage of 4.7 gigs of gpu memory and a whopping 8 gigs of system memory. I remember bf4 using a lot of memory in its beta as well. After release and later with patches the memory usage went down. Also, the fact that this game uses so much system and gpu memory, doesn't mean that it needs it to run well. I have also seen some microstuttering in outside areas. This coincides with my gpu dropping below 99% usage, which normally indicates a cpu bottleneck. Although I doubt that is the cause in this case, since the cpu didn't come close to 100% on any of the cores. So probably an optimization issue.
Just like the original game, the freerunning is great, but the combat is barely mediocre.
EDIT2: Quantum Noire has made a nice video, which is more atrictive to watch, then to read this post
https://www.youtube.com/watch?v=vgPuXrvV3tAAlso this game "forces" you to hold a controller like it was ment to. So index finger on the shoulder buttons and middle finger on the triggers. I am sure that a lot of people are used to this way of holding a controller, but I am not. I prefer to have my index fingers on the triggers; maybe because I have small hands, or maybe because it is just the way I have learned to use a controller.