Show was probably one of the most uneven shows I can remember. Some episodes were truly transcendent, while many others just grasped at it. Season 1 was probably the best, as the characters served to show us a town (as a proxy for the world) dealing with the crisis of the departure. Seasons 2 and 3 drifted gradually away from being about the world to being about the individual characters. Season 2 still gave us a different setting (Miracle) to expose us to the hysteria of the post-departure world, but after the setting was established, it settled into the character drama. Season 3 went full-on character drama.
There was only so much entertainment value that the various little easter eggs could provide. Stuff like the same man being in Kevin's hotel and on Matt's boat ("God"), the hysteric man ranting about a nuclear event in the airport only to be followed by the crazed Frenchman launching a nuke, Kevin's pacemaker scar after Kevin's twin brother's heart implant, etc. That kind of stuff was enjoyable and made it mildly rewarding to be a fan of the show, but it wasn't enough to carry the show as a whole.
It was a demanding and somewhat ambitious series, that sometimes hit its notes. Props for doing something different.