I have a 2011 IMAC and I couldn't use it for work at home because it wouldn't update past Yosemite.  I needed something inexpensive and specs to meet what I needed for work.  I was a little hesitant at first due to this being a refurb/renewed item.  I ordered it and a few days later, I was up and running.  This unit boots up super fast and I'm able to produce more work at home with this little machine at home and in the same amount of time than being at work. The unit looks new and I haven't had any issues with it.  Currently, I am using this unit for work only.  256 GB of storage is just not enough.  In my opinion, overall it is a good unit.