The leak is from late 2013, and they’ve said it was before they fixed some pretty large stability and rendering bugs, and they’ve also said they wanted to provide as stable a release as possible, so I’m sure the current version will be okay.
Also they will be patching it as time goes on too to fix any issues, as well as re-add the stuff that was too unfinished at the current time (minor things like visible hands on the steering wheel, a simple skill progression system, etc.)
here’s a wonderful panorama because it’s still so god damn cool
Some notes about their engine - it’s based on the 1.007 patch that GSC never publicly released, and they also worked with GSC and got access to the source code to port visual features from CoP and such. It also supports more than double the amount of objects as CoP, hence the extreme amount of overgrown vegetation in the maps.
Also the main benefit of DX11 in CoP was the better optimization and tessellation, and DX10 is supposedly extremely optimized now so it kind of negates the need for DX11. (tessellation would be nice, but only a few of the STALKER models work well with it.)