This sonata, dated February 1789, is Mozart’s penultimate sonata and it did not become known until five years after his death when it was published for piano and violin. This sonata was excluded for a time from his set of sonatas even though Mozart had clearly entered this work into his catalogue as “for piano alone” and the violin part has been considered as not having been composed by Mozart.
Mozart labelled this sonata as “for beginners” and it is often regarded as a teaching piece however considerable ability and sophistication is required to bring this sonata to justice. Jane Magrath, in her excellent book ‘The Pianist’s Guide to Standard Teaching and Performance Literature’ published in 1995 states “the first movement is especially suited for a sensitive, lyrical performer. A finely honed legato is a requirement for the slow movement, while the concluding rondo needs good finger technique. The entire sonata requires musical maturity”.
A number of examination boards have used all or some of the movements of this sonata as exam pieces. For example, the Allegro (first movement) is in the RCM Grade 9 syllabus, the Adagio (second movement) and Rondo (third movement are in the RCM Grade 10 syllabus, the complete sonata is part of the Performer’s Certificate (TCL) and the Allegro (first movement) is in the current TCL Grade 8 syllabus and was in the ABRSM Grade 8 syllabus in 2003-2004.
According to Arthur Schnabel “the sontatas of Mozart are unique: too easy for children, too difficult for adults. Children are given Mozart to play because of the quantity of notes; grown ups avoid Mozart because of the quality of the notes”.
From www.henle.de website “Those wishing to get to know Mozart’s gentle, slightly elegiac side should play the opening movement of this lesser-known piano sonata K. 570. The second movement, too, marries the calm strains of horns with a somber melody in C minor. Only in the spirited B-flat major finale (“Allegretto”, in alla breve metre) does the mood shift to restrained gaiety”.
From www.allmusic.com website “The opening Allegro is quite light in character; although on an altogether more modest scale than the sonatas composed earlier in the decade, it is masterful in the way it wrings various structural and contrapuntal implications from its deceptively bare opening. The Adagio is a rondo with two episodes that sets out to beguile rather than convey profundity. The final Allegretto bubbles with humor and surprise effects; it is one of the many finales in which Mozart evokes the world of opera buffa. Musicologist Alfred Einstein called the work "perhaps the most completely rounded of all of the Mozart piano sonatas, the ideal of his piano sonata.””
There is a lecture on this sonata on the Great Courses website - https://www.thegreatcoursesplus.com/mozart-piano-sonata-in-c-minor-k-457