These 'Brilliant Boxes' represent something more than just value for money.
To my inexpert ear, the orchestra plays, and the choir sings, with style and, one senses, enjoyment. The soloists are more variable, from adequate to good. So for any particular cantata the performance is not likely to be the best.
But for me the great bonus is that, at the price, these boxes bring the idea of having a recording of every cantata within reach, and so many of the cantatas, even those less well known, have marvelous movements, which I would never have encountered otherwise.
And it is intriguing to come across movements which, recast, Bach was to use in other works such as the B minor Mass.