Additional receptacles on 20 amp service using quick holes on back
That type of outlet is what we call screw-and-clamp (or I stubbornly call it screw-to-clamp).  Here's a great page comparing the two. 

There is nothing wrong with screw-and-clamp. The only caveat I have from the rare times I've dealt with them, is set your torque correctly. Undertorquing will make the wire(s) pop right out when you shove it into the box.

Using the word "quick" to describe screw-and-clamp is something I strongly discourage, because the trade name for that other thing is "Quick-Wire". 

(For some reason, manufacturers are reluctant to use our preferred pejorative, backstab, for the jab-and-forget-until-half-the-circuit-goes-dead-for-no-reason types). 

In the early days, UL approved backstab connections which were dual-rated for #14 and #12 wire. But these had problems and they were forced to backpedal from that, because the cheap springs (4 for 50 cents) didn't have the range to grip both wires properly.  (also, accepting #12 copper also meant #12 aluminum could fit, and #12 aluminum is legal in 15A circuits, but that copper-only termination couldn't support it.  This is made worse by copper-clad aluminum being out there, forcing you to look at the wire end to determine type). 

One time I was running a dehumidifier and the plug felt warm.  That shouldn't be.  The socket was warmer. So I popped it open and found a #12 stranded wire shoved into the backstab. 1/3 of the strands just splayed all over the place.   Stranded wire is a great application for screw-and-clamp, because it helps unraveling to super-twist the wires, and that's a lot easier to do on a straight wire than a shepherd's hook.