In the following years, Schuster's position was solidified with operatic successes in Naples and Venice. He was also recognized in Germany as an accomplished composer and his singspiel,Der Alchymist, oder Der Liebesteufel is considered one of the finest examples of the art form. Most of his works are assigned to the opera buffa, but he also composed religious works, chamber music and orchestral music.
Schuster's work is also found in the string quartets appendix of the Köchel catalogue (No. 210 et seq,), and for a long time the "Milan Quartets" (1772–73) were viewed as Mozart works. Schuster composed these works around 1780, which were long considered to be copies of Mozart originals. The musicologist Ludwig Finscher was able to uncover the true origin (in The Music Research, 1966). He died at Dresden.