The resin is very light and quite flexible, its not as brittle as other resins I used. Its also very light, much lighter than an equivalent size model in plastic. Just to be safe I did wash them. There didn't seem to be any residue but its always better to be safe. Apparently, this stuff is also non toxic. As I don't normally go out of my way to inhale resin dust, I can't comment.
Upon close examination, the models are much crisper than their metal equivalents, participially the armor platting. There isn't that slight melding that you used to get with the metals.
Overall, I am very impressed with these guys, fine work on GW's part.