Among some other new features, I find the folllowing features the most interesting.
- The Citrix Receiver client now allows the VDA's operating system to control the session resolution.
- Windows Continuum is now supported by the Citrix Receiver, so your session will adapt whether or not you are using a tablet or 2-in-1 device.
- You can use multiple monitors with different DPI settings, both in published application and published desktop mode.
- H.265 hardware video encoding mode support. (you need VDA 7.16 or higher)
- There are new registry value settings you can set on the client to optimize HDX bandwidth over high latency connections (https://support.citrix.com/article/CTX125027)
The full list of features can be found on this page.
Until now I discovered only 1 drawback but it's a really important one: This version of Citrix Receiver does not support Windows Server 2008 R2 as the VDA's operating system.
If you are still running Windows Server 2008R2 on your VDA's, I would suggest to migrate to Server 2012 R2 or 2016. To be able to migrated, you need to migrate your Citrix environment to version 7.X since XenApp 6.5 is not compatible with Windows Server 2012. EASI will be happy to help you if you would require further assistance on this operation.