It was supposed to be the change that ended all the gimmicks. It was meant to be the real price war that lowered prices across Tesco stores and brought some much-needed relief for shoppers.
So it's a bit of a blow to discover that the cost of a basket of shopping has actually gone up.
The Grocer magazine mystery shopped all the big supermarkets for a basket of 33 staples. Embarrassingly for Tesco not only was it more expensive for these items than either Sainsbury's or Asda, it was also £1.34 more expensive than it had been before the so-called war started last week.
The basket contains a mixture of branded and unbranded goods - including things like meat, cheese and pasta sauce. The idea is to test the claims the supermarkets are making... and things don't look good for Tesco.
It was caught out by a number of price rises in its basket, including a 69p increase in Birds Eye Chicken Pies from £2 to £2.69 and own-brand Parma ham was up 63p to £2.45.
This is pretty shaming for a supermarket that has just pledged dramatic cuts across the store, and that you could trust it to be cheaper.
The new research contrasts with studies done at the beginning of last week which showed Tesco was the cheapest among the big brands - although fell far short of Aldi and Lidl. So how can this be possible?
The problem is, of course, that whether your shopping is getting cheaper or not depends entirely on what you put in your basket. Tesco didn't pledge to cut the price of everything - it pledged to cut the price of 3,000 of its most popular goods. If your shopping strays outside of these things, you are just as much a victim of fluctuating prices and overcharging as ever - as a 69p price hike on a packet of pies goes to show.
So sadly we can't just trust to the slogans and the price cuts. We still need to shop around if we're going to get the best deal, and we still need to take the supermarket claims with a pinch of salt.
Some things never change...