By now, you probably already heard about new release of Civil 3D - called Autodesk AutoCAD Civil 3D 2015. If you would like to give it a trial run and see how it works, you can download free trial version from here.
The first thing you will notice when you open it is that the interface looks different using that dark theme. Next is optimizing graphic performance and stability when working with larger models. This is platform change that comes from vanilla AutoCAD. We may write about that in the future in greater detail but for now let’s cover some significant changes in Civil 3D.
We continued with 2013-2015 model interoperability. For the most part you should be able to go back and forth between versions. There are some specifics you need to be aware of and they are documented in help.