Hi Antonio
With the 3Dpdf creator as far as I know does not produce the shadows that you see in the sketchup file, and it does not re produce the light from the light fittings that you can put in your model.
You can however change the default lighting of the whole model in the settings of 3Dpdf creator or in the actual pdf when it is open, by selecting the desk lamp icon and choosing a setting.
Link to more some examples http://forums.renderplus.com/wiki/index.php?title=RPS_3D_PDF_Samples, and more info http://forums.renderplus.com/wiki/index.php?title=RPS_3D_PDF
Your right its a nice piece of software, and very useful in my work flow, as I can send clients simple 3D models, that they can read instantly as most people now have Acrobat Reader on their computers. The best bit is that they can then move easily move around it and give me quick feedback.
You can also get your clients to do load the sketchup up viewer and send them the skp file, but I find most prefer them as pdfs.
There is also a dedicated RPS Forum at http://forums.renderplus.com/, where your can put your questions/queries
Richcat