In case you haven’t seen this post on MSDN yet, take a look so you know what is deprecated in SharePoint 2016 IT Preview.

https://msdn.microsoft.com/en-us/library/mt346112(v=office.16).aspx

I assume more will come to help us all understand what has changed and what is different. To get a quick update of what is new then use this link:

https://msdn.microsoft.com/en-us/library/mt346121(v=office.16).aspx

And of course, if you want to download it you can use this link:

https://www.microsoft.com/en-us/download/details.aspx?id=48712