You give no indication of your current level of playing so it is somewhat impossible to state this piece's level of "difficulty".
With that said, I could tell you that physically, I found this piece is rather akward to play; the first movement, for example, contains many,
many notes, jumps, octave jumps, and is still to be played extremely fast. (In fact, written in the coda is something like "as fast as possible" and then later "faster"
). The fourth movement demands much control and stamina, especially in the area of forearm rotation. Second (gorgeous!) and Third mvts are not so bad.
However, even more, I found this sonata to be challenging interpretatively. First mvt: Because of just an insane amount of notes, it is difficult to bypass the "thick" texture and sometimes odd phrasing so that it does not stand out as just a bangy loud mess of notes. Especially with this sonata, you really have to master the technical difficulties in order to show off the beautiful melodies and excitement. I could probably say the same about the last mvt as well.
Though I learned much on how to interpretively mold a piece of music so that it becomes at least somewhat understandable to the audience (or so I tried!), I must admit that I personally found other Schumann pieces to be more enjoyable and satisfying to
play, such as the Carnival of Vienna.
Looks like you can find a pdf of the Sonata here:
https://www.abrahamespinosa.com/partituras2.htm 
Topic: Schumann - Sonata in G Minor op.22