You can get more than passable real time rendering. The main problem is that a very high end machine is required. The Octane Renderer is a real time renderer aimed at stand alone rendering (think movies). Theres also the Brigade engine (by the same people) which is not currently public. You can find impressive videos of it running on this blog.
They were at siggraph'12 with this demo (video). As you can see, if the scene and camera are still the image converges very quickly and looks quite impressive, but constant movement causes grain artifacts, presumably from limiting the number of bounces per frame. It isn't competitive with rasterization because of this grain and the hardware requirements, but I think it will only become more viable as video cards get cheaper and more powerful.