According to Osho, the Great Bliss is the state in which the ego—the felt 'I am'—is forgotten forever. Ordinary happiness are brief egoless gaps evoked by beauty, love, or music; misery is proportional to ego. Great Bliss is continuous egolessness: being a nobody, unobstructed, one with existence, independent of outer triggers.
Great Bliss is when the little voice of “me, me, me” is gone for good, so the quiet joy you taste in a sunset stays all the time.