It is a little bit hard to distinguish the separate graphing areas from each other, although they are different colors; they are separated by lines which look just like the axes.
The instructions are incorrect: the maximum x0, v0 and a0 are 90, 9 and 1.8 rather than 100,
10 and 2.
The sliders make it difficult, sometimes, to set a particular initial value.
The bright backgrounds of the graphs are distracting.
Use of the item beyond lecture/demo requires the instructor to supply assignments or other written material.