If it works like the previous time, basically you can open individually 1 square for 10 coupons, or open everything for 700 coupons. If you believe you can find all 9 tailed beasts in less then 70 tries manually, you can go ahead and do this. Each non tailed beast square also contains some points, these points can be redeemed for ninjas/items as per usual redeem trade.

As to whether or not it is worth it, we need to see the redeemable list first once maintanence is over. Also different people value items/ninjas differently, some have no qualms spending 10k for a ninja, others wont spend 4k. Same with the item drops like cave keys.

Edit:
Oh the guy above me explained better, haha :P

Pity new players that are now unable to farm lucky board for med threads. Guess it looks like majority of redeems being for ninjas are now permanent.