I bought my first macbook this summer, Mac Book Pro 15" late 2013 model. Best computer I've ever owned by far. I am kinda hesitant about downloading 10.10 with so many who claim they are having trouble with it so I will probably wait couple of weeks to see how it works out for everyone. Questions, Do you lose any of your data? Will any of the settings be changed? I really enjoy using 10.9 and I back up the Mac every 2 weeks on a portable hard drive. I just don't want to go threw the hassle of setting every thing back up like I have it now with 10.9. Thanks.