Cinema 4D is simple, because it is sensible. Unlike Max, there are no piles of features buried under piles of other features (most of them not used much). Unlike Truespace (and Blender, for that matter), there is no quirky GUI to cause premature baldness. Unlike Lightwave, the workflow is easy to understand and follow.
All the most used features are accessible at the click of a button. Parameters for functions are all grouped into sensible locations. Modelling is really a no-brainer, but packed with features, and flexible enough to accomodate industrial visualisation or flare of artistic inspiration. Shaders are easy to create, and one of the most powerful in existance.
If you’re doing product visualisation or broadcast-quality animations, C4D is a highly commendable package.
PS: As much as I like C4D, I agree that the viewport controls suck. One of the very few complaints that I have about the program. Another complaint I have is using the object tree… I find it very un-intuitive to use, for reason I cannot pinpoint.