I really like their chocolate (really good quality high cocoa dark chocolate), bread flour is cheap, as are organic eggs. DP really loves their continental pilsner lagers in a bottle. Also you can get nice sliced bread cheap, e.g. a multiseeded loaf for 89p whereas at other supermarkets they would cost £1.30 +. Goats cheese is nice, as is their bags of grated parmesan, really fresh and good quality.
I personally think their fruit and veg are good and really good value. Often there are offers on, e.g. got a big punnet of blueberries, can't remember how much, but less than a pound and would usually cost at least 2 elsewhere. Avocados are always ripe.
I secretly love the quattro formaggio pizzas in the chiller, really thick and doughy and cheesy so totally not what pizzas are supposed to be like but really good hangover food! Also like the breaded camembert/mozzarella in the freezer section. Frozen pizzas are good too (their own brand).
Nappies are good and very cheap, but still think asda are better, but their wipes are the best cheap ones out there. Really thick and good quality like huggies, but about 89p.
Their cheapest pasta also has a really good bite and tastes a lot more expensive than it is (dp is very particular about pasta and can tell cheap stuff a mile off but he will eat this).
You've just reminded me how good lidl is! Have been getting Sainsburys online for convenience but reckon I may pay Lidl a visit soon!