This depends on your needs, of course but with that caveat... In 2013, my early 2008 15" MBP had gotten annoyingly slow. I wanted a new MBP, but I couldn't afford one at the time, so I bought a refurbished late 2012 Mac mini i7, 2.3 GHz, with 1 TB HDD. I was quite happy with it. The next year, my wife's 2009 white MB also was showing signs of aging. She only does basic stuff, so I bought her a refurbished 2012 Mac mini i5, 2.5 GHz, with 500 GB HDD. It was fine for her needs. In 2015, I bought a new MBP and intended to sell my Mac mini, but I never did, figuring it was good to have a second computer as a backup, and maybe a home media center. By 2017, though, our minis, thanks to their 5,400 rpm spinning hard drives, had become annoyingly slow. They're still selling for top dollar on eBay, so I once again considered selling mine. I wanted a 5K iMac but couldn't justify spending that kind of money right now. I'd considered adding SSDs to our minis, but I wondered about the wisdom of upgrading five-year-old computers. I also was concerned by the number of stories by people who had ruined their minis while performing the upgrade. I watched the OWC videos on performing the upgrade and decided I was up to the task, having been an electronics technician while I was in engineering school in the 1980s. I had a 1 TB HDD lying around, and I ordered OWC's 120 GB SSD upgrade kit, planning to upgrade my wife's mini with a Fusion drive. I figured that, if I screwed things up, she could have my mini. I took my time performing the upgrade, and all went well. I couldn't believe the speed increase! She has over 20,000 photos in Photos, many thousands of emails in Mail, and a large iTunes collection. Instead of bogging down with the spinning beach ball while scrolling through these apps, things glide quickly. Satisfied with the results, I upgraded my mini with a 3 TB Fusion drive. For what I do (photo editing, amateur videos, WordPress development), it feels as fast as my 2015 MBP. My mini is now my desktop workstation, with two 1080P monitors attached, and I use my MBP when I don't want to work at my desk. Having a base station with all my peripherals always attached is easier than continually docking and undocking my MBP. So to those of you wondering whether it's worth adding an SSD to a 2012 Mac mini, I think it is. Processor speeds no longer increase by leaps and bounds every year, so a 2012 Mac mini isn't as outdated in 2017 as a 2007 Mac was in 2012. As for projected lifespan, my 2000 G4 tower ran for 10 years before it died. My 2008 MBP and my wife's 2009 MB still work fine, although they're unusably slow. Whether it's worth buying a used 2012 Mac mini with an HDD at the prices they go for now is another question, but if you already have one, and it's too slow for you, but you can't afford a brand-new Mac, adding an SSD will give your mini new life.