Fuller Maitland, Johann Sebastian Bach: His Work and Influence on the Music of Germany, 1685–1750, was published by Novello & Co in three volumes.
Especially Karl Hermann Bitter's comprehensive Bach biography, published a few years before Spitta's, all but disappeared in the folds of history.
Papers on specific aspects of Bach's life or compositions invariably go from the assumption the reader is familiar with what Spitta wrote on the topic.
Spitta's comprehensiveness and thoroughness made it difficult to come up with a competing view on any aspect of Bach's life or work.
A major development from the late 20th century is that high quality facsimiles of all kinds of primary sources regarding Johann Sebastian Bach became more readily available.
It was no longer necessary to gain access to protected archived sources to make a detailed comparison between Spitta's writings and the artefacts he commented upon.
From Spitta's biography Bach's character is evaluated rather negatively: choleric, aggressive, narrow-minded about a broader cultural context, religiously bigoted, stuck in an obsolete contrapuntal style, depressed with a negative impact on his output in the last years of his life, lacking modesty, frustrated about his presumed lack of success, in short, a man impossible to get along with.
He uncovers a Bach broadly acclaimed in his own time, composing without interruption when confronted with bigotry and well-aware of what was going on in cultural life.