I withdrew around 1 hour ish ago and it still has not arrived in my wallet , so definitely not instant with me.
Every time I saw that complaint about a Just-Dice withdrawal, I asked the person what wallet they were using, and they always said "blockchain.info".
It seems that the b.i wallet often doesn't see unconfirmed transactions.
Arent the withdrawals manual? So it might just be that no one approved the withdrawal...