That's a physical based approach if I recall, so it's supposed to be more realistic in most aspects but it usually (or used to) takes a lot longer to get a final render, as the renders are done in passes, with each pass improving the overall quality. The tech has been around for awhile and there are arguments both for and against the approach but it's a popular rendering method and you'll find many appss/plugins offering the option. Maxwell is a popular one, as is Indigo.