[6][4][7] A concept album, it is a sequel to 2016's The Similitude of a Dream and both are loosely based on The Pilgrim's Progress by John Bunyan,[8] besides having similar covers.

[13] The album was released as a two-CD package, a special edition with a bonus DVD featuring behind-the-scenes/making of videos, and as a triple vinyl version.

[7][6][1] The album's title was suggested by drummer and vocalist Mike Portnoy, based on the last line of The Similitude of a Dream, which says "let the great adventure now begin".

[7] Writing for Jesus Wired, David C. Coleman said "the members of the band musically complement each other to an extraordinary degree, creating a whole far greater than the individual parts" and pondered that "overall, The Great Adventure is not quite as earth-shattering as the career-defining The Similitude of a Dream but it's still a remarkable accomplishment and fitting conclusion for the tale of The Pilgrim's Progress.

He praised all members' performances and finished his review by saying "while it's no doubt a little early yet to make any claims [about the album being better than its predecessor], The Great Adventure easily comes pretty damn close.

The production is flawless" and that "the collective known as The Neal Morse Band rises to the formidable task of matching their most celebrated work, The Similitude of a Dream, proving they continue to grow and heighten the quality of their musical output.