The initial experience with OS X upgrades is almost the same every year. Check out how to get macOS Sierra from outside the Mac App Store.
That was after the MAS download got interrupted 6 times in a row, and I had wasted more than 15 GB of data on a single download of 6.08 GB. It was only a few hours back that I was successfully able to upgrade my Mac. However, my experience with the upgrade process was not a pleasant one. The OS upgrade is highly recommended as it vastly improves the performance of Macs (that are capable of running Yosemite). I was very excited about the release of OS X El Capitan earlier this week.
