Traditional, like most of Liebermann’s work. It owes parts and moods to Field, Chopin, Liszt, Fauré, Debussy, and Alkan, but it owes its most effective passages to Messiaen (measure 24 and parallel passages, in which triplet sixteenth-note figures in octaves frame quieter passages) and older composers like Scarlatti and even Frescobaldi (measure 40 and parallel passages, which are simple canon-style counterpoints in unadorned quarter and half notes).
The piece is a Liszt-style sonata in that it’s a continuous movement, with outbreaks of scherzo-style movements. It’s also a quasi-rondo form, because the initial nocturne theme returns in successively more intricate forms.
The final appearance requires difficult counting: fifteen against six (measure 113). Other than that it’s easy to play for intermediate pianists.