Radiosity makes a potentially boring room composed of 4 flat, featureless walls (and ceiling, and floor) and a single omnidirectional light source look beautiful. You'd see subtle shadowing along the walls towards the corners, due to that area of the walls being less exposed to the lit-up walls adjacent to it. I could render up a quick demonstration in MAX if I still had it installed. But here's my old Amaunet rendered with radiosity - notice the darkening along the inside of the 3 necks, where they join the body; every corner is darker than either of the surfaces that meet at that corner. That's the effect of radiosity.
IIRC it was Ryx who actually rendered that pic... IIRC.