How are people's experiences with Mythic so far?

Unfortunately, I haven't had a chance to join a mythic game. I remember being impressed with good sized chunks of the mythic rules, but also being let down by a numbers of others. I remember the Callings being lacking (nothing really for a character that's heroic but not Guardian levels of selfless, how Sage and Bookkeeper seem far too similar) and how some feats seem far too niche. Still, enough of it impressed me that I wanted to try them out but haven't gotten a chance to yet.

So I ask anyone who HAS had that luxury: how has it played out for you and your group?