it's not just the holiday schedule per rkkwan

they are Orthodox Jews- so they close friday afternoons (which is very early in the winter) and all day saturday

the holidays actually begin the night before, so you will find them closed on the afternoon before - as early as 1:00pm

but they are without a doubt legitimate- which is more than can be said about most NYC electronics stores (J&R and Adorama are fine)

do some product research before you go-