A Christmas PlayStation Store sale begins with a bang today by offering Metal Gear Solid 5 half-price, which means £30 on PS4, £20 on PS3 - markedly cheaper than in most shops. Catch is, the deal only lasts until tomorrow (Wednesday 2nd) at midnight, as it's the first of 12 Deals of Christmas.
Certainly bodes well for the others.
In addition, there are fixed discounts to a number of PS3 and Vita games that last until Christmas Eve. They're collected together in a Games Under £12 section on the PlayStation Store. Given most games have been out for a number of years, you're bound to be able to pick them up cheaply in many places. I've been looking and looking but none of the deals grab me.