I gave my old 2012 2.5ghz mini to my daughter's family for Christmas and they love it. I set it up with an external USB SSD as the system drive and upgraded the RAM to 16gb. It's a respectably fast little machine. An internal SSD will make yours even faster, especially if it's the original Apple SSD, I have a quad 2012 mini with the Apple 256gb SSD and it's very fast, only takes 15 seconds to boot to the desktop.
Some people install their own SSD's in these machines, and that should also be fine if they chose a good device and installed it properly. OTOH, people have been known to damage their mini's by doing their own installations so caveat emptor there.
The other nice thing about the 2012 mini is that RAM is easily upgraded and it's cheap. You will probably be fine with 8gb but it's good to know that you could bump it up to 16gb in the future if needed. Now one issue might be the old HD4000 graphics chip. It's fine for my use, but might be a constraint for some newer graphic-intensive apps. However, Apple still supports it with Final Cut Pro and BlackMagic even supports it in DaVinci Resolve.
These machines still appear to be in demand and the pricing on used ones is often rather high. So you need to weigh all of this against a new (or Apple refurb) machine with a full warranty. IMO, there is little doubt that the base 2012 mini is a better computer than the base 2014 model that replaced it however.