Short shelf life. Hard to grow. Prone, ironically, to decomposition. Genetics are tricky. Specialized skillsets and knowledge and equipment often necessary for cultivation. Is it more efficient than raising tasty beef? Sure. Does it still taste great? Oh yes. Is it efficient? I guess it depends on what kind of efficiency you're aiming for. I've grown oyster mushrooms multiple times before at home, and it can be difficult, rewarding, frustrating, and fun. YMMV.