Today Blender’s internal render engine is only good because of the node editor.
However Maya’s tree system is in my view still more capable than Blender.
Blender is getting into it’s knees the moment you turn on raytracing.
But with AAO area lights and some slick material mixing you can create very decent renderings
with Blender only.
Big Buck movie is a great example of it.
I am texting VRay right now and it is great. The new Yafaray is out and while missing some materials it is pretty easy to use and produces great results.
I am curious where 2.5 will go to since the API for external engines should be improved as well.
Problem I see is when Blender internal and External engines have different materials.
I also see the great value in Blender because of the node editor.
Material nodes are useless when you want to render with Yafaray or other engines.
But also render layers and passes do not work with external engines.
It would be interesting to see how external engines can be embedded into Blender so they
can at least use the compositor for post production when not also for materials.
I think material node should be very easy with 3Dlight or similar system because of the nature of those shader languages.