I tried an alpha version a long ago, in my opinion it will be a resident evil styled game except with realtime graphics that are superior. It's not that revolutionary, but for real time stuff sure I guess, but, there are many companies out there today, it's alot more competitive but with ID's reputation and Carmack, ya it'll be something.
When games have full HDRI+Radiosity outdoor lightning and other advance raytracing techniques in real time.. games will be truly realistic