There is a lot of controversy on how this piece should be played. Chopin marks it Lento con gran expressione. Lots of people rush through this piece and play it too fast. The middle section is where I hear a lot of people making mistakes. Particularly, in measures 31-41 leading up to its return to the main theme. Preceeding this is a few measures marked Adagio that hear many student pianists ignoring. The trills in this piece are what get a lot of people, too. When the trill is preceeded by the same note as the upper note in the trill the note should begin on the principle note. This song was featured in the musical the Pianist, fun facts.