Greenstuff is the normal putty Gw has, it is reasonable to work with, there will be some articles on the mainpage soon for GS working and mixing etc.
GS is good for details, milliput is better for larger stuff and is able to be carved and filed.
But GS you can use different mixes of the parts to make the properties different. If you want more info either Pm me and Ill help and once the article is up Ill send it to you.