Yes, that's really the missing piece and sounds great. Before that it really felt isolated, like working in a VM. My use-case was to have a full featured bash for invoking some build scripts built still to be able to utilize some windows executables (most imporantly currently docker for windows) in it. Seems like this should do it.
Yes, I also use git bash / msys currently and I'm pretty happy with it. But there were a few cases were it caused problems, e.g. the automatic translation of file names caused some headaches for me (in most cases you want it, but e.g. in docker statements you don't want it). Wanted to try whether WSL can even improve that. The old version was unfortunately too limited, but this update sounds very promising and I will test it again.
No more so than any of the shells that's already available on Windows (batch scripts, WSH, Powershell). If one was to exploit scripting on Windows, it would make more sense to target the existing shells rather than Bash as they're more widespread on Windows.
Plus Bash on Windows isn't a new thing: we already have Cygwin, MinGW and I believe there was also some native Windows PE ports too. This is just a better implementation than the aforementioned three.