The writing throughout this season has been a mess. We have had some good development but as soon as they started with the whole time travel plot, the show became tedious. That said Ben Linus and John Locke are pretty much the only characters that have kept this show interesting from the start of season five onwards. Sayid has had good development. Other main cast members though are starting to become more background characters now.
Review of The Incident: Part 2
