His compositions were once considered bad imitations of his father's, but modern scholarship has changed the opinion of his importance. He is now considered to be a composer that wrote during the transition from the Baroque age to the Classical age, in the gallante style of the times, and some music more serious in nature. W.F. wasn't much better at tending to his own compositions as those of his father. There is no way of knowing how many of his works are lost.
The Harpsichord Concerto In E Minor was written about 1767, roughly the same time as Haydn wrote his 35th Symphony, Mozart was 11 years old and already an accomplished composer, and Georg Philippe Telemann died in Hamburg at the age of 86 (and his godson C.P.E. Bach took over Telemann's position of musical director of Hamburg the same year). The work is written for strings, continuo and solo harpsichord and is in three movements:
I. Allegretto - The concerto opens with a robust theme for strings. After this is played through the soloist enters with its own theme. The rest of the movement involves these two themes as they are replayed and varied in an early version of sonata form, which W.F. Bach used in his compositions. There is also a feeling of Sturm und Drang in this first movement, and W.F. has recently been acknowledged as one of the earliest composers that used this stylistic trend. After the two themes have been thoroughly explored, there is a cadenza for soloist. After the cadenza, the first theme is repeated by the strings and the movement ends.
II. Adagio - The strings begin the movement, after which the soloist enters. The harpsichord steadily plays rather benign music, with the strings providing the seasoning of the movement by sudden outbursts. There is an extended section for the soloist without strings, after which the strings appear and play the thematic material while the harpsichord plays a commentary, and the movement ends with one last sigh.
III. Allegro assai - The music moves back to the minor as the strings begin the movement by playing another robust theme. The soloist enters with commentary on the theme while the strings interrupt with the biting motives of the opening. And so the movement goes until the soloist plays a short solo, and the strings return to the robust theme of the beginning.