I think this is a fantastic deal and have just signed up.
Free USB Dongle
£50 cash back after 3 month (credited to account. No need to send in redemption vouchers etc)
Half price line rental at £7.50 per month with 3GB allowance.
12 month contract, not 18 or 24 which you typically see.
Over the course of 12 months you will pay £90 in line rental. Minus the £50 you receive via cash back the total cost is only £40 for the entire year! Works out much better than the existing £39 PAYG deal currently out there.
I called 191 from my voda mobile and spoke with the upgrades/saves department to get this deal. However, everyone should be able to dial 0808 0220055 which is the number I received via text from voda notifying me about this deal.
Btw, you also have the option of choosing between the white or black dongle. Although they're the same I chose black just because it's newer :)