Definitely an incredible show. My feeling is that while I loved Nora's story at the end and how it seemed to make sense of the whole Departure thing, it really was just a story. She didn't travel to the other side and meet her family. She chickened out at the last second and then hid from Kevin in Australia until he finally found her.
The theme of the last episode seemed to be about pretty lies, that if you thought about them long enough or learned enough facts, would start to unravel themselves and you find their ugly truths. The wedding guests are told the doves released with their wedding wishes will fly all over the world, but they can't actually fly more than 50 miles. Nora's in on that scam. The nun that she works with has taken a vow of celibacy for her faith, but she's secretly sleeping with the priest. Kevin claims he happened to run into Nora on vacation in Australia and only now has a chance to ask her to a dance that he tormented himself over not doing for twenty years, but he was really just too afraid to confront with the baggage of their past.
Nora claimed she went to the other side, the Departed were there, found her family were living happily back in her old house, then found the scientist to make another machine and send her back. If the scientist had made his way over in the first place, don't you think there would have been some sort of worldwide effort on that side to build a new machine to send everyone that wanted to go back? How would Nora have been able to convince him to build that machine when the rest of the world couldn't? How would she afford for him to build that machine? I don't think these were oversights on the story writers' parts, but intentionally designed flaws to make us as the audience eventually doubt her tale when we processed it for ourselves.