For my part i play Two Worlds 2 (PS3) , i have plyaed Raisen (PC) and i find that the Depth Of Field make the scene look great ! Its' not an FPS you don't need to spy on very long distance.

On Two Worlds 2 indeed the Depth of Field is dynamic and adapt to situation if for example you play a ranger and enter zoom mode with an arc !

One thing great is that with DOF , you can have very low
polygon for objects using LOD, you won't notice how polygons
are low due to the DOF.
So in fact DOF can be a big use for frame rate in some cases; like the old techniques using FOG or clipping.

I propose to make Depth Of Field switchable in option menu