Criminals often struggle with the midgame when the corp has managed to rez enough ice since the criminal breaker suite tends to be relatively inefficient. Rubicon Switch is a way to use an economical lead in the early game to prolong the early game. By spending as much as the corp did to rez a card and spending a click you undo the rez, forcing the corp to spend credits the next turn all over again.
Because Rubicon Switch requires a click you cannot use it during a run and since ice is normally only rezzed when you run into it you will have to face a piece of ice before you can derez it. And if the corp rerezzed it and you hit the switch again, same deal, you have to run into it to get it to rez first. Of course the second time you know what you're up against.
Also note that Rubicon Switch only works on the turn that the ice was rezzed. That can be a problem when for example you run into ice that gives you tags and need to spend your remaining clicks to clear the tags. In that case you have to choose between floating tags or not using Rubicon Switch.
Because Rubicon Switch only works on one piece of ice per turn if the corp manages to rez multiple pieces the switch is not nearly as effective. Which is why it's important to employ Rubicon Switch in combination with the good old criminal strategy of economical devastation.
There are some pieces of ice that Rubicon Switch works very well against and some that it's horrible against. The first category consists of ice with an additional nasty cost such as Archer or illicit (bad publicity cost) ice. The second category, where Rubicon Switch is weak against, is ice that has a higher printed rez cost than effective rez cost, most notably space ice (Asteroid Belt, Nebula, Orion, Wormhole).