Dad introduced me to it before university, because offal is cheap and healthy and magnificent. I'm not a fan of kidney unless it's heavily mixed with something, like a steak and kidney pie, for example. Liver is glorious when prepared well, as Mirage said, but horrible and flaky and dry and awful when done poorly, so watch out for that! Lamb's liver is usually very good quality, and in England it's cheap as piss!

Heart is good, though you've gotta work for it. Big muscle and whatnot. Chicken hearts are easy to come by in China, but the best heart I had was ox heart. Holy trout. I diced that bad boy up and made sandwiches. Rocket fuel sandwiches that could power you through an entire day and give you the meatiest and most horrendous gas ever. I think you'd like heart, Locky! xD

Intenstines are a big no. smurfing abominable things.