A couple of points to mention and clarify here:
1. the Mini-14 was introduced in 1974, as mentioned by others. At that time, the US military was firmly wedded to the M16, and Ruger has no illusions or intentions of having the Mini replace or supplant the M16. In the beginning, they used the following phrase to market the firearm: "the world's most expensive plinker". It's a fitting description.
2. there are TWO versions of the Mini, and they have different characteristics: the Ranch rifle, and the regular model. The Ranch rifle has a VERY CRUDE backup iron sight in the rear, and uses a fixed ejector. As such, it really launches the empty cases out of the action with some vigor. The regular model uses iron sights very similar to that for the M16A1 series rifle, and uses a bump type ejector. Those rifles have very mild ejection, and the sight adjustments are done with a bullet point or punch, like the M16A1.
3. when fed with Ruger factory magazines, the Mini is probably as reliable as any self-loading firearm. The complaints of reliability generally stem from use of questionable aftermarket magazines, because no one wants to pay the rather steep rate that exists for Ruger factory magazines.
4. to the best of my knowledge, I have heard of VERY few Mini's with actual parts breakage. The design is robust, if not terribly accurate.
5. based on everything I have read from all the various Mini owners, I would put the accuracy of a typical unmodified Mini on par with that for a typical SKS, M1 Carbine, or AK, firing equivalent ammo.
My stainless Mini, bought back in 1980, isn't terribly accurate, but for a general knock-about carbine that is pretty much maintenance free, it fits the bill.
I put on a Choate combination flash supressor/military type front sight, and a hooded aperture on the rear to improve the sight picture to more closely match that of an M1/M14. I feed the thing my M193 ball-equivalent reloads all day long, and have put probably 3000 rounds through it flawlessly over the past 25 years.
Is it as accurate as my AR-15 I use in High Power? NO. Is it fun/reliable? YES.