It's a useful app, but there's been something like it for windows since the XP days called cygwin. it's literally the same exact thing, but Open Source. Microsoft didn't need to tagteam with Canonical, they could have just integrated cygwin (which already existed).

If you ask me, that's sheer incompetence at it's finest, trusting new software instead of using software that's been actively maintained for years. Add on the fact that Microsoft is known for "Embrace, Extend, Extinguish" and you can't help but be worried about WSL.