Seemless upgrade of a 14 year old Imac that, while still usable, was showing signs of becoming unstable (frequent intervals of the "beachball of death". I was able to connect both Imacs to transfer files with ease and as to be expected found the new system much faster. I encountered problems with wireless connections to my printer (a Brother MFC 7360N) but resolved thes through a wired connection. It has the same screen size as my older system, but requires less space on my desk. I am currently running both systems side by side but will eventually mothball the old system. The Retina screen display is very good.