re: using Unix tools on Windows, I do like that you can pipe the output of a program in WSL to the Windows clipboard (clip.exe). I was really surprised by this! I use pbcopy on the Mac for this all the time.
It's implimented as a magic filename? Not a virtual or real file that actually appears in a filesystem? You don't have to do something like mount a virtual fs that maps to your host windows fs like a bind mount or nfs mount, and also add that fs to PATH?
The entire point of WSL is seamless integration. Windows drives are automatically mounted as /mnt/c, the Windows PATH is added to the Linux one, and it can run Windows .exe files and communicate with their standard I/O.