As a renderer, it's pretty terrible. Many other renderers beat it in physical accuracy, e.g. cycles, vray, octane, mitsuba.
But it does what it needs to do to spit out a pixar movie, so it's clearly the best in the world at doing the job pixar designed it to do.
So I guess if you want to make pixar movies pretty much exactly the same way pixar makes them, it's not going to get any better than that.