Seems like a good deal for students. I know of a few people who are sitting on the fence with hit and miss speeds so could be a good way to test reception @ Uni or home without committing to contracts etc. Check Whirlpool for some feedback. Be aware the network in Syd and Mel doesn't cover the whole metro area.
I have copied the relevant parts from their page below
vividwireless is making a special O-week Offer to students in metropolitan Perth, Sydney and Melbourne. For a limited time only, you can purchase a refurbished* USB modem for only $19 and receive a free 3GB data voucher worth $29.
Purchase the refurbished USB modem online now and you’ll also receive a free 3GB data voucher! We’ll also waive the $10 delivery fee. But hurry, this Offer is only available while stocks last.
We’ve limited this Offer to 1 refurbished device per customer so that as many students as possible can take advantage of this great Offer.
*USB modems are refurbished and may have been used for testing purposes or returned by customers outside coverage area. They have been checked, tested and re-packed. 6 month warranty.
†Bonus 3GB data voucher included with the purchase of a refurbished USB modem. Voucher valid for 30 days from activation or until data allowance reached. Voucher can only be used at the time of activation and is for single use only. Offer may not be combined with any other special offers or discounts. Not redeemable for cash.
What network does it use and is it locked ?