Heart is delicious, especially in a balsamic-vinegar reduction coupled with southern german dumplings as a side dish.
Liver is good, if you get rid of the "hide" and all other piping in it and don't overcook it.
I prefer to cut it in smaller pieces, my buddy prefers bigger chunks(floured). All together with caramelized onions. Great!
Or mince the liver and mix it with the german dumpling (spaetzle) dough. Prepare normally, fry liver spaeztles in pan with onions and scramble eggs over it.
I usually fry up the kidneys as well. Great tenderness!
Heart, liver etc. contain essential vitamins. Without those, your body will starve to death. Oh yeah, right, you take vitamin pills...