The penalty for eating human meat isn't too severe, but the penalty for mistakenly trying to sell human meat at the Junk Market is very severe (though you do get one warning). For that reason, I would suggest leaving any human corpses alone.
With the right traits, non-cannibalistic food is pretty easy to come by. If you're at serious risk of dying, though, eating a human is better than starvation.
The "going crazy" penalty for eating human meat for too long is a greatly increased hunger rate. There is flavor text describing much worse effects, but currently there is no other in-game effect.