CorelCAD 2013.5 is available as an update to all CorelCAD 2013 users as of today!
Go to Patches & Updates on the Corel web site to download the update for your platform (Windows 32-bit (x86) or 64-bit (x64), or Macintosh).
Besides fixes and improvements of existing features in CorelCAD 2013 there is also a number of new tools and features that come for free with the update:
Mac users now benefit from 64-bit application power with CorelCAD 2013.5 on all 64-bit Macs (Mac OS X 10.6 and newer).
Note to Apple Mac App Store users: Please note that CorelCAD as purchased on the Mac App Store will not include the Batch Print feature in the CorelCAD 2013.5 version. There are still limitations in the Mac App Store application version caused by the Sandbox operation mode that is required for a Mac App Store application.
While CorelCAD has unique capabilities to import CorelDRAW (CDR) files and also export complete CAD projects or parts of it directly to CorelDRAW, it primarily follows commonly known CAD applications paradigms. The UI elements such as the command window and the supported command aliases are known by many experienced CAD users.
The timing for your comment is excellent as the new CorelCAD 2014 was just released yesterday!
One of the major new features for Windows users is the introduction of Ribbon UI workspaces. This is not mimicking the CorelDRAW UI, but it should get you very close to what you're used from many other Windows applications these days.
For learning CAD from the ground up you may want to take a look at the "Inside CorelCAD" book which covers all the basics for getting started with various CAD tasks and workflows using CorelCAD.