It's a little crazy that Roku has no YouTube and no AirPlay equivalent. Twonky Beam sort of bridges the gap, but the experience is terrible. I really wanted to replace ATV with Roku3, but I ended up switching back.
I've got a MacBook, iPad, and iPhone, and I still love my Roku more than my old AppleTV. The only issue is that the AppleTV has better options for watching sports, but Plex alone more than makes up for that.