Loving this game so far, it's like Ass Creed meets Batman
I have a 4670k @ 4.1Ghz, 16GB RAM and GTX 980 @ 1.3Ghz. I'm running it on ultra (including textures, with motion blur set to camera only to get it working) and getting 60FPS (with very rare dips to 55) on a small down sample from 1600p to 1200p native.
Big thanks to the poster that mentioned about alt tabbing to fix the triple buffer issue in full screen mode It means I have better down sampling options thanks to using DSR, which doesn't seem to play well with borderless window. Using borderless I was running it at 150% resolution which was just a tad too much for my setup in some cases (it was dipping to around 45 which felt jarring as hell), but using full screen with DSR tricks the game into thinking that my native res is 4K . This means I get to choose, 67%, 70% etc which are all above native res and give me some breathing space.
I kind of wish they had implemented some AA options though, I mean it's OK with the downsample but I'd love for a bit of TXAA or something similar on there. I tried FXAA as someone here suggested but it didn't seem to touch the jaggies and just blurred the fuck out the textures. I'm normally fine with FXAA but it looks exceptionally bad in this game. That said I don't notice the jaggies 90% of the time thanks to all the crazy action so it's all good.