980 and i5-4690k here.
Running game at a locked 30FPS at 2560x1440p on a 120Hz GSync monitor.
This title looks SUBSTANTIALLY better in motion than these screenshots would suggest. Is it a far softer image than I'm used to? Yes. Downsampling from 4k gives me the clarity I would expect from a native 1440p image but I can't maintain 30FPS at that internal res.
The character models, Lincoln especially, look as good as the ones in UC4. And the game feels smoother at 30FPS than that title did for me - no awful ghosting on camera pans. It's not ideal, but it's more than playable.
Also, it does not look worse than Mafia II. As someone who replayed that game before this came out, trust me, it's a generational difference and NOLA looks amazing, as do the NPCs. As for the UI - it's tiny and in the far corners of the screen for me. There's a resize option in the menus. It would be nice to disable some stuff but it's taking up minimal screen real estate as is at my res.