What are the limitations of the Windows Subsystem for Linux?
From the WSL FAQ:
Can I run ALL Linux apps in WSL?
No! WSL is a tool aimed at enabling users who need them to run Bash and core Linux command-line tools on Windows.
WSL does not aim to support GUI desktops or applications (e.g. Gnome, KDE, etc.)
Also, even though you will be able to run many popular server applications (e.g. Redis), we do not recommend WSL for server scenarios – Microsoft offers a variety of solutions for running production Ubuntu workloads in Azure, Hyper-V, and Docker.
There is also the official test for the Linux Test Program that provides some insight on pieces of software and if they work or come close to working.
The 2 links above are the official stance. One of the things Microsoft notes is that WSL does not aim to support a graphical interface. Users though have been able to run xfce and unity.
When someone can get unity to work on WSL I doubt there are any limitations. Lots of WSL is unproven ground so to get something to work might be up to the user (ie. in this case you ;) ).