Sick and evil.
> Sick and evil.
Why? As mentioned, one of the chimera was a pig that had human blood. Pigs (or other critters) with effectively human organs would make marvelous hervestable sources of blood, organs, tissues, etc. Make a critter that does nothing but spit out human stem cells, and you'd really have something useful.
A mouse with a brain made from human brain cells would not have a human brain. It would still be packed within the mouses small skull, and would be mouse-dumb. It would, however, likely be suseptible to human brain disorders such as Alzheimers and the like, and thus treatments that work on a mouse would be directly transferable to humans.