How difficult is this piece to play?

It depends on your current level. That piece is an LRSM (Licentiate of the Royal Schools of Music) exam piece. Meaning that it's equivalent to the level required of 3rd year piano majors in a conservatory. It may not look that hard because of the even rhythms, but it's actually quite hard to play well - there are countermelodies, inner melodic lines and the such contained within the steady stream of notes. You don't want it to sound like an exercise by hammering all the notes equally without regard for the melodic contours, harmonic progressions and the subtle nuances of colour in the writing. I've heard many young pianists play it when they're musically not ready to tackle that piece, and it just sounds plain awful and annoying - like a machine gun pounding your ears with sound all the time. The tempo will also be a challenge to anybody. However, if your technical skills are stable enough and you're mature enough musically, it's definitely a great piece to play, if just for the sake of challenging yourself. It took me at least 4 months to learn it properly, with all the harmonic colours. All the best!