Derivative of what? There were black astromechs in the OT.
http://www.angelfire.com/droid/astromechs/page11.html
well, i guess i may be wrong then, but it still feels derivative to me. on first glance it looks exactly like someone took R2 and put a paint job on him reminiscent of vaders shoulder armour from his reveal at the end of ROTS. thats why i called it derivative. but i suppose we have found prior art. its just, choosing the most reconizable droid, and giving him a new paint job, isn’t what star wars needs in these new movies. or isn’t what i want at least.