Sharing in case helps others avoid having trouble.

Update worked fine - once update completed fresh reboot - gdm starts fine - can login - but after that get a blank desktop - nothing at all works.

Will go over logs more carefully but looks like gnome-shell is crashing:

Process 1181 (gnome-shell) of user xxxx dumped core.

The logs are tricky, as gnome spits a slew of error messages at the best of times (this is not new to 43, for me anyway).

All 3 machines are intel i915 based; 2 NUCs and an older laptop.

I've downgraded to 42 and all works well again.

FYI :)

gene