OK, i gave it a spin last night and its very nice indeed, although HW demanding. My system is Core i7 980x @ 3,78 GHz, 24 GBs of RAM, geforce gtx590, win 7. Installed on SSD. Since Nvidia GPU, no Mantle, just D3D.
Few random thoughts>
i tried the RTS only with high difficulty (not extreme) and the FPS plummeted on occasion (zooming out, rotating camera) to 0-10 range.... i take this is down to GPU not being fast enough (played it with just one GPU, not both, equal in performance to cca GTX570), that CPU would be fine to run it without stutter otherwise....or not?
turning the temporal AA off helped the performance quite a lot. It ran almost fluidly, without any major hiccups, i dont think the FPS dropped under 20, atleast i did not notice.
the graphics were not so great 
. I mean, i expect bit more. Obviously the smallish fighters, when you zoom in onto them, are completely on another level polygon- and detail-wise, when you compare them to fighter/bomber models from Rebellion. But the specular highlights were bit over the top metallic, it seemed like the models lacked some kind of bump or normal maps...it kinda looked bit cartoonish. Was not blown away by the lighting solution in general - CryEngine it is not. Maybe this was only down to art direction, rather than technical solution though.
Do not want to sound pessimistic or what, it was indeed cool otherwise and i cant wait for another Sins (or any other potentially similar game in general) to be released on this engine.
