I got tired of running Linux directly on my desktop. Compiz crashes (worked in 14.04, not working in 14.10, started working again in 15.04, not working in 15.10...), can't keep my select sound output, terrible font rendering, awful HiDPI support, graphics drivers are a mess, and on and on...
Since I basically just need the non-graphical parts of Linux (Bash + Tmux + Vim) I'm very happy with this setup.
PS: Forgot to say that I have a very beefy machine (Skylake Core i7 4Ghz, 32GB DDR4, fastest consumer NVMe SSD from Samsung) but I've found that this setup works well on basically any machine.
For this use case, "Ubuntu on Windows" seems to be a nice improvement.
It's a very convenient arrangement for developing web apps/servers. I have the servers running on FBSD which can be accessed from a browser on the Windows host. This perfectly replicates connecting to a remote server, so when the app is working properly and committed to the repo on the remote host, it's almost guaranteed to work as intended!
When I acquired the SP2 I originally thought I'd dual boot. Turns out that's difficult to accomplish, but in a way using Hyper-V is better because I have Windows and FBSD running at the same time. Of course the VM imposes limits so not optimum for every purpose but good enough for my uses.
I should mention that Cygwin is installed as well. Runs Bash nicely in a terminal, and a good way to ssh to remote servers as well as FBSD in Hyper-V.
msysGit is also handy when using a Windows host.
Rsync is straightforward and has fewer permissions issues to work out when sharing with Windows, but is uni-directional. NFS is a true share rather than a sync, but restricts what you can do to the directories on the guest in terms of permissions. There are other options too, like bindfs and unison, but I haven't personally explored those in depth.
I sound like a Vagrant fanboy or shareholder but I'm just a very happy dev since I started using this setup.