Watch the thread where we talk about the various issues. Zentyal isnt built to be stable its built to be tinker-friendly anyways, since 3 or so. I could never have it in a production environment, especially since devs don't seem to have the bugs everyone else is having. That said, if you only need ad integration and a hardware router then, you should download the update. Samba IS broken totally, more so than 4.2. Command line works but zentyal changes prevent that from working through a reboot. GUI is lacking half the time, but it is on ubuntu proper so you can just use the command line to install whatever you want, thats what I do.