I upgraded my Win 8 laptop and then downloaded Classic Shell to make it run more like Win 7. I was running Win 8.1 under Classic Shell also. Other than a very slow process (5 hours), I haven't had any problems. BUT on my main computer running Win 7, I'm going to wait until October. I read that there will be a large update then and some computer experts are recommending holding off until the major update is done. In the meantime I have to put up with the VERY ANNOYING Win 10 notification popup screen. I wish I could disable it.