The Turtle Renderer is great but it is not very expandable yet. There are limited Utility nodes still. Turtle is still a v1 package. It doesent support post process rendering no layered shaders or ramp shaders. Other than that has some great features that will rival the competition. you should definetly check them out. I have been testing there stuff for a bit and I am very impressed with some of the features. some big stuff I like at the moment

-ambience occlusion
-sub div rendering (take low poly model and automatically render Higher res)
-bump mapping allows multiple files into one node

There is alot more.