From the T&Cs for the above offer:
"The Offer is subject to a fair usage policy of 50MB per month and is not to be used for other activities, such as non-Orange internet based streaming services, voice or video over the internet, peer to peer file sharing, and non-Orange internet based video. Should you exceed the fair use policy or if such use is detected, notice may be given and Network protection controls may be applied to all services which Orange does not believe constitutes mobile browsing. This may result in, at Orange’s discretion, your inability to purchase the Offer, a reduced speed of transmission, suspension of data browsing services and/or suspension of your account."
How can that be fairly described as unlimited?
More like an all-you-can-eat buffet where you can only have one spoonfull of food.