When releasing the season for reviewers, Lindelof took the unusual step of revealing most of the season (all except the finale). I think this is the first review released so far.

Very minor thematic spoilers for S2, but a few passages are copied below:

http://www.indiewire.com/2017/04/the-leftovers-season-3-review-final-masterpiece-1201801201/

‘The Leftovers’ Review: Season 3 Pushes The Best Show on Television to Evocative New Heights

Damon Lindelof and Tom Perrotta's final season is a masterpiece more in tune with the moment than anything you'll see this year.

Season 3 is no less than a coup, wrapping up a wild narrative with ambitious new threads and honing in on each character’s fundamental spiritual and psychological beliefs. This final round with the Garvey family is designed to evoke powerful emotional reactions; you’re as likely to startle your dog from cathartic laughter as you are from open sobbing, all within the course of an hour.

This is a cumulative story, and it’s designed to be a cumulative viewing experience. Standalone episodes and arcs are a glimpse of the full story’s power, but dedicated study of both prior seasons will amplify your appreciation of the new year.