As far as the goods are concerned I've not had a problem with the major items, sure a few of the parkside things like drillbits have let me down on occasion but the bigger ticket things are seemingly just very good value - my pillar drill 500w, german made (not chinglish as assumed by Rhyolith) 3 year guarentee etc etc is better in just about every way compared to a similar priced one from any major tool retailer - I know because I was looking ahead of time. 3 years on almost and it's still humming away nicely - along with a lot of the other power tools I've bought.
Another thing many of you have overlooked to mention is that as well as the mainstream supermarkets having more choice, this also adds to an incredible amount of unsold product, both food and other goods. How much this adds to their general overheads I can't guess but it must be significant.
Also I've noticed more and more mainstream supermarkets opening and closing branches seemingly willy nilly, we had a small morrisons "express" that had been shoehorned into a small site open and close within 18 months or so - could have something to do with that fact that there was already a large asda and sainsbury's not much more than a mile away, but this seems to happen a LOT.
Our local B&Q closed down, it was one of their biggest stores in the area to start with, then it got cut in half (the other side left empty) and now it's closed altogether, I mention it because I found out some while ago that that site is owned by the large sainsbury's on the other side of the road, they must have bought it when that small commericial park first opened, but now it sits idle not making any revenue - I have to wonder how many more sites are owned by the big supermarkets, usually to earmark it as a potential supermarket location, but not utilized yet and not generating income; because all of that will add to their yearly losses and be a reason to keep prices higher than maybe they could be.
Lastly, right after the crash of '09 did anyone else notice how all of a sudden prices just came tumbling down, and with the major campaigns of Aldi the last few xmas's and poundshops flourishing everywhere prices came down again? I'm certain I never used to see quite so many items being offered in major supermarkets for a pound. Even now I wonder how is it places like farm foods can sell 3 tins of heinz baked beans for £1 when they are around 60p per tin in a major store.... and then you look around and it's obviously the Lidl / aldi effect: small store, sparse choice and basic presentation.
I don't know about you but I don't go to a supermarket to be "entertained" with the adult equivalent of a babies sparkly mobile overhead.