All of the major characters/actors return, to some extent, for the season. Sullivan Stapleton, Jaimie Alexander, Rob Brown, Audrey Esparza, Ennis Esmer, and Ashley Johnson all do excellent jobs in their roles, especially the last two. I will not spoil how things play out, but some of the highlights of the season are learning Patterson's first name, more Bill Nye as Patterson's father, and cameos from most of the various characters who have appeared throughout the series run (mainly in the series finale) with the one notable exception being Marianne Jean-Baptiste. The series finale presents fans with two different endings without ever identifying which was the real ending, leaving things open to interpretation, which was a very novel way to end the series.
The DVD set is a three-disc set. It is a very bare-bones MOD DVD release. There are English captions but no extras at all, just the episodes. It would have been nice to get some behind-the-scenes material or commentary tracks like those included in the Blu-Ray releases for the first couple of seasons or to get a MOD Blu-Ray release to at least get the episodes in HD. Still, the reality is that the show was not popular enough to garner a Blu-Ray release now that physical media (especially for TV series) is going the way of the dodo bird. So, really, the only reason to get the DVD set is if you have purchased the prior seasons and want it to have a complete collection. Otherwise, you are much better off streaming it.