Tried to download and install Yosemite last night. Blew half of my monthly ISP download allowance. Wouldn't install. Just sat there. Displayed messages with CMD-L. Nothing happening. Had to restore from SuperDuper backup. Thanks for another crappy experience Apple. Wasn't iOS 8 bad enough? If you're going to continue to give us this crap, at least you should provide thumb drives of the crap so we can actually re-try things without having to install fiber cable to our homes.