I have one of the RCBS Primer Pocket Swagers, and it works quite well, although it is a bit slow. Other than a Dillon 1050, I don't think any method of swaging primer pockets will be any faster. ReloaderFred and ocabj have given a good description of the swager and how it works.
The only issue is the size of the ram on your reloading press. The case stripper sleeve that comes with the RCBS swager has a 1.000" I.D., so it only works with a ram that is one inch or smaller in diameter.
I use an RCBS "Big Max" press, also known as the A-4, which has a ram 1.250" in diameter. When I bought the primer pocket swager, I called RCBS and explained that the case stripper didn't fit my press. They sent me a new case stripper that is also 1.25" in diameter, so the swager works well. No charge for that new case stripper, by the way.
I measured a couple of other presses that I have in the shop, and most have a ram that measures 1" or less. If yours fits that description, then the RCBS at $23 is the way to go. I have a Lee Classic Cast Press with a ram that measures 1.125" in diameter. Of course, the original case stripper wouldn't work, but the larger one (1.250" for the A-4) does work on the Lee Classic Cast press.
If you have a press with a ram larger than 1" in diameter, but no larger than 1.25", I would call RCBS before I buy the primer pocket swager, and see if they still have the larger case stripper available. They didn't charge for mine, so availability seems to be the only question.
Jim M