I have been a few times and love it, both the food court and the supermarket. There is not a giant Japanese supermarket anywhere near where I live, so for me it is a nice cultural experience to wander the aisles for an hour and ponder mysterious foodstuffs. On one of these trips I bought a jar of umeboshi (sp?) and then made the mistake of eating one. I guess you have to eat those things in childhood to get a taste for them.
The second time I went there it was on New Year’s weekend and it was absolutely heaving with people. Apparently it is a thing to go for New Year.
