Downton Abbey: The Grand Finale appears in an aspect ratio of 2.39:1 on this Blu-ray Disc. The movie offered a fine transfer.
Overall definition seemed positive.  Virtually no softness materialized, so the movie appeared accurate and concise.  
I noticed no signs of jaggies or edge haloes and shimmering remained absent.  The film lacked print flaws and seemed clean.
The movie’s palette opted for a distinct sense of teal and amber.  These appeared fine within the film’s stylistic choices.  
Blacks seemed dark and tight, and shadows demonstrated good clarity.  This added up to a satisfying presentation. 
A character drama wouldn’t seem to be a candidate for a whiz-bang soundtrack, and the Dolby Atmos audio of Finale fell into expected realms. Downconverted to Dolby TrueHD 7.1, a few scenes – mainly related to crowds or a horse race – used the various channels moderately well.  
Usually the track remained oriented toward ambience and music, though.  As such, don’t expect lots of sizzle from this restrained mix.
Audio quality satisfied.  Although didn’t get much score, the music was full and rich, while effects showed nice clarity and accuracy.  
Speech – obviously an important factor here – appeared concise and crisp.  Nothing here soared, but it all seemed perfectly adequate for the project.
As we shift to extras, we open with an audio commentary from director Simon Curtis and actor Elizabeth McGovern.  Both sit together for this running, screen-specific look at story/characters, sets and locations, music, cast and performances, and the finish of the franchise.
Occasionally we find some modest nuggets of information here, and the track improves somewhat as it goes.  However, the track remains largely dull and doesn’t give us many insights.
Five featurettes follow and Changing Times runs 11 minutes, 33 seconds.  It involves Curtis, McGovern, screenwriter Julian Fellowes, producers Gareth Neame and Liz Trubridge, and actors Michelle Dockery, Hugh Bonneville, Raquel Cassidy, Jim Carter, Michael Fox, Kevin Doyle, Sophie McShera, Lesley Nicol, Phyllis Logan, Allen Leech, Brendan Coyle and Laura Carmichael.
The show looks at story/characters as well as cast and performances.   "Times" mainly acts as a way for all the actors to say goodbye, so we don't really learn much.  However, fans may enjoy this farewell.
Society Season spans 13 minutes, 25 seconds.  Here we find remarks from Neame, Bonneville, Fellowes, Dockery, McGovern, Carmichael, Curtis, Leech, costume designer Anna Mary Scott Robbins, choreographer Diana Scrivener, production designer Donal Woods, historical advisor Alastair Bruce, hair & makeup designer Anne Nosh Oldham, musical director Martin Hall, and actors Harry Hadden-Paton, Alessandro Nivola, and Simon Russell Beale.
We hear about sets and locations as well as costumes, choreography, and music.  Expect a mix of fluff and facts.
Next comes Authentic to the Core.  It lasts seven minutes, 13 seconds and features Neame, Fellowes, Curtis, Bruce, Dockery, Bonneville, Robbins, Woods, and actors Arty Froushan, Dominic West, Joely Richardson and Paul Giamatti.
Via "Core", we learn about Noel Coward and his involvement as a character in "Finale" and other stabs at more costumes, locations and period realism.  Unsurprisingly, it comes with some useful material and some self-praise.
A Farewell to Fans goes for two minutes, eight seconds.  It involves McGovern, Carter, Dockery, Hadden-Paton, Leech, Nicol, Bonneville, and actors Joanne Froggatt and Penelope Wilton.
All sit together with others who don't speak to wax about the series' impact. I like the fact "Fans" combines so many actors in one spot but it tells us nothing of use.
Finally, Downton Abbey Celebrates The Grand Finale occupies 42 minutes, six seconds.  Hosted by Michelle Dockery, we also get remarks from Carter, Bonneville, Logan, McGovern, Carmichael, Fox, Leech, Froggatt, Carmichael, McShera, Nicol, Cassidy, Wilton, Robbins, Woods, Giamatti, Cassidy, Hadden-Paton, Doyle, composer John Lunn and some fans.
Across "Celebrates", we get notes about cast and characters as well as music, costumes, some production elements and various memories/anecdotes.  Abbey lovers will likely enjoy the interactions among the actors but this show exists solely to promote Finale so we don't learn much along the way.
As the conclusion to a long-running franchise, Downton Abbey: The Grand Finale brings a tale with a little more plot than usual. That makes it a bit more interesting than the prior two films but it still delivers a project most likely to appeal to diehard fans.  The Blu-ray comes with excellent picture and appropriate audio as well as a decent though inconsistent collection of bonus materials.  Established Abbey buffs will probably enjoy this fond farewell but it seems unlikely to enchant others.