I have an old, 1980, Mini 14, and it is true that it is certainly no bench gun. The biggest problem is the pencil thin barrel that vibrates and plays hell with accuracy. Accuracy can be improved greatly with a barrel stabilizer. The sights suck big time on the older guns and mounting a scope sight is an exercise in futility. The trigger sucks but can be improved if you know what you are doing.
Another reason to steer clear of the Ruger is magazine availability. After market magazines are not reliable. Ruger mag's usually are, but they are expensive. And you can't just slap a mag in the well as you can with an AR or AK. It takes technique.
Nevertheless, despite my criticism, I have owned the rifle for over thirty years because I like it's "feel". And shooting offhand inside fifty yards, I can hit with it about as well as I need to assuming my needs are not great.
I do also have a scoped AR for those times when I want to hit things at 100+ yards.
Don't know what changes were made on the newer model Mini. Hopefully they used a heavier barrel, improved the sights, made provision for a scope mount, and improved the trigger.
I like the Mini and in some ways I prefer it to the AR although it isn't nearly the gun the AR is regardless of the maker. I can think of only two reasons to buy a mini over an AR and that is preference for the looks and feel of the mini. In terms of performance, versatility, and reliability, I'd go for something else.