Unless you have a GPU from the very latest generations, don't expect to be able to run Assassin's Creed Unity anywhere near the top end, as its recommended specs are pretty steep compared to the last AC game.
The minimum specifications for the game suggest at least an i5 2500K running at 3.3Ghz, along with 6GB of RAM and a GTX 680 or HD 7970 graphics card.
It will also need at least 50GB of storage space for installation, much like the recently released Middle Earth: Shadow of Mordor and The Evil Within.
However what is a little bizarre is that while the recommended specifications are a bit tougher to match, graphically they're pretty similar. Yes it does recommend a much more expensive i7 3770 running at 3.4Ghz, or an AMD FX-8350 at 4Ghz, but the GPU is only one generation better than the minimum: a R9 290x or a GTX 780.
These GPUs aren't that much more powerful than the one specified to run the game at a minimum fidelity, so why is the minimum so high? It looks to be to do with video memory once again.
While developers at the moment, specifically Ubisoft seem to have trouble hitting anything higher than 30 frames per second on games built for the current generation of Microsoft and Sony's consoles, due to high shareable system memory in those systems, high resolution textures aren't much of a problem. However those levels of memory on a PC are a little harder to come by, which is why it seems such hefty GPUs are mandatory for Unity.
Pretty as it is and all.
[Thanks NeoGAF]