The overall animation is quite smooth but the only critique I have to offer is the lack of metallic definition. In the texture, assuming that you constrained the metal concept, should have a type of embossed gloss on it. To show both dynamics and general sheen of the metal. As in efforts to make it both conceptually deep rather than a paper feel, because as the texture of it standards right now, it gives of the conclusion that all the panels are flat and have no dimension, angles, or anything of that sort.
Such as these sticky note smilies
compared to the smilies on MSN that show a slight embossed appearance through shading.