So far so good.  The casters make it seem a little wobbly as there is a lot of play in the caster rotational connection plus they do not lock all that well.  I placed a heavy stand mixer in the open part and that has helped to ballast the island, but as the mixer is too tall some new holes for the shelf need to be drilled.  I may also add some wood glue into the paneling grooves to give it more lateral stability.