Seems like a decent deal if you're a regular customer. There's limits on how often you can use the vouchers and you can't use multiple together but if that's fine with you then save yourself $60.
From the email:
Valid only for EB World Members. One Side Quest voucher per month can be redeemed per EB World Member. Vouchers expire 30 days after delivery. Not redeemable for cash and non-transferable. Not valid for purchase of preorders, laybys, digital currency, and gift cards. For full terms & conditions visit www.ebgames.co.nz/ebworld/terms
From the website:
Join now and unlock something awesome!
What is Side Quest? It’s a new voucher subscription available exclusively for EB World members. Simply pay $60 and get $120 in EB Games vouchers over the next 12 months.
How it works:
Each month, for 12 months, you will receive a $10 voucher to spend on games, loot, accessories and more at any EB Games, store and online. That’s $120 worth of vouchers for only $60!
Your first $10 voucher is sent within 24 hours and is valid for 30 days from activation. You must activate your voucher within 30 days of receiving the email to your EB World email address, or it will expire.
Example:
* Purchase Side Quest for $60 on 7 September
* Receive first $10 voucher no later than 11.59pm on 8 September
* Activate voucher 9 September.
* Voucher expires 9 October
* Second month voucher received 8 October, cannot be used in conjunction with first months voucher
* For full terms and conditions visit //www.ebgames.co.nz/terms
Only 1 Side Quest subscription per EB World member. Duplicate Side Quest subscriptions will be cancelled, and you will be contacted regarding a full refund.
Basically you'll have to use a voucher for at least 6 months in a year to get your money's worth. Not so good for casual gamers.