The trio begins and ends in F major (the minuet however is in f minor (all in 3/4)). In the A section we have a four bar phrase in F that ends in an IAC, followed by a contrasting, modulating 6-bar phrase that cadences in a PAC of the key C Major (V). These last two bars serve somewhat as a cadential extension and ensure that the listener here's the PAC in C rather than a HC in F. Ergo, we have a contrasting, progressive, assymmetric period for the A section, heralding an open or continuous binary form.
Moving into the B section, we continue with the same rhythmic and melodic contour as the first phrase in the A section, only now it serves as a sequence. The motive moves up and up in the right hand over each bar and the left hand moves down and down a half step each bar. This produces a nice contrast in the voicing. In the fourth bar of B, it cadences in a HC in C. Although the left hand takes up the melody as it did in the second phrase of the A section, the right hand switches to static, full-bar, octaves, and instead of cadencing as it does in the A section, in the third measure, the right hand joins in in octaves with the left hand, thus introducing an entirely new texture and moving into and even more transitional and developmental section of B. At measure 59 the texture switches drastically to fourths in the right hand and one voice in the left hand all moving in chords that change with every eighth note. After four measures of this new texture propelling us wildly forward, we suddenly come to a grinding halt, but still no real cadence. The dynamics draw back to p and then pp and the piano moves to full-bar chords. This lasts for three measures, and ends on a half cadence in F Major (thus we see in retrospect how what had come before functioned as a transition back to the original key) and then we return to the orginal eight bars of A, only this time the second phrase does not modulate and does not have an extension (thus the two antecedent and consequent phrases are symmetric), but finishes on a PAC in F Major--like a good rounded binary form.
To summarize: open, rounded, binary