Stainless steel knives as the name implies are very difficult to rust or discolour. Pushed to their absolute limits they certainly can still rust but it takes a lot of mistreatment for that to happen. Generally speaking if you've used a kitchen knife before you've probably been using a stainless steel one and if you're just getting into cooking and Japanese knives this is where we normally recommend you start. Japanese stainless steel is special because of the added carbon content which provides better edge retention and Japanese makers grind their knives thinner behind the edge which gives them a better cutting feel. Stainless steel knives are easier to maintain but in general don't have the same edge retention or ease of sharpening as carbon steels, even Japanese stainless steels. There are of course higher quality stainless super steels (R2/SG2, HAP40, Cobalt Special) available these days and these types of stainless steels will compare with carbon steels but are usually more expensive.This isn't the rule, but generally speaking, if you want a stainless steel that is comparable to carbon steel in terms of edge retention and ease of sharpening you will need to spend more on the stainless steel knife than you would on the carbon steel knife, hope that makes sense.