Grimm, in his Correspondence littéraire, called Eckard ‘the strongest’ of all Parisian composers, stating that ‘he has genius, the most beautiful ideas, with a manner of playing full of feeling and an extraordinary lightness’.
de La Borde, who declared in 1780 that Eckard's execution at the keyboard was ‘the most brilliant and pleasing’ and that ‘he excels particularly at preluding for entire hours making the time pass as moments for those who listen to him’.
Burney gave further testimony to the high regard felt for him by his contemporaries: There are many great German musicians dispersed throughout Europe, whose merit is little known in England, or even in their native land; among these is Eckard, who has been fifty years at Paris.
Although the title-page of op.1 specifies only the harpsichord, Eckard's preface extends the performance of the work to the piano; and his meticulous indication of dynamic shadings (e.g. no.6, second movement), a practice previously unknown in this period, clearly shows his preference for the latter instrument.
The texture is enlivened at times by the contrapuntal involvement of the left hand; and in an effort to make the accompaniment of greater musical significance, Eckard did not restrict himself to the Alberti bass pattern, but used it rather as one of several devices.
Although his thematic material is not particularly distinguishable from that of his contemporaries, Eckard's ability to develop it anticipates the mature works of Joseph Haydn and Wolfgang Amadeus Mozart (e.g. op.1 no.2, first movement).