It looks good, but I would be pissed personally (if it was my first shotgun, or given to me by a family member........this would most likely be given to the firstborn that showed interest in shooting) But who knows, he might not like his brother too much.
Be prepared to buy it from him (or replace it with another single shot shotgun) or at least offer to do that to help smooth things over if tension arises. You could easily pick up a shotgun IN THE ORIGINAL CONDITION FOR 50-75 bucks so its not a totally bad situation if the worst happens. Better to start with someones old shotgun, than their car or motorcycle.