Well it is finished in the sense that I am over it and have a decent enough final render, sort of a studio shot type thing.
Materials, modelling, lighting etc could all be worked a bit more and tweaked further for a better result, but I want to move on to something new. It is my first time with a lot of this, specifically materials and rendering, and I learned a lot from it, so I am happy with it.
All modeled, rendered and composited in Blender 2.57.
EDIT: I spent some time tweaking the shell material, and a little bit of tweaking the lighting: