We love Lidl mostly because of the price. Almost everything was/is around 20-30% less than the stores around it. Much of this is from 'store brand' items, but the price diff is lower even against other 'store brand' pricing.
When they opened, they had a wider variety of items, including a wide variety of daily baked breads. That got scaled back a lot, as apparently there's not enough support/demand in this area for fresh breads outside of 'white'.
There's a weird circle of grocery stores that have sprung up in my area. Within a 3 mile radius, there's Target, Walmart, Lidl, Aldi, Wegmans, Food Lion, Harris Teeter, Publix and Lowe's (2?). It seems excessive to me, but the area is growing, and they likely wouldn't have invested in this area without a strong expectation of not losing money.
There's still a Lidl stigma around here. Many folks I talk to think of it as some 'poor person' shop.
I don’t know if I eat cheaper at Lidl but I eat better. The cheese and meat sections alone - I have probably twice as many charcuterie boards now that a Lidl moved in.
Aldi-Nord isn't that different, I'd say, at least not when free standing, in their standard layout. The only difference is the glaring white LED lighting they have. That is bRrRr!
Oh, and their electronic payment works fast. Had to use that recently for the first time in my life because I thought I had more cash on me. Wave card, enter pin, ZAHLUNG ERFOLGT! Phew!
(Yah Yah, I caved in, I know...)
edit: Aldi-Nord has better spices, though not all the times. Their Tandoori-mixture is very good, at least compared to the dozens of others I've tried. (In those small 80g aluminum cans) Ginger powder is also acceptable for me.
However, most of the times I just skip them, because I have 2 excellently managed Edekas available, and they have it all!
When I talk to British friends, the idea of shopping at a Lidl seems to be sacrilegious to them. Still, when I went into one somewhere in Yorkshire before the plague, it was pretty much what I expected.