Is the Guardian being ironic with this?

In last Saturday's Review section, Stuart Kelly gave the new Irvine Welsh novel A Decent Ride a right kicking. His critique concludes: "If anyone parts with £12.99 for this, they're being taken for a ride."

Directly underneath that was an in-house ad giving readers the chance to order a copy of the book's hardback edition - at the discount price of £9.99 [not including postage and packaging].

So, where the sub-editors being ironic, disingenous, or didn't they even notice?