Aldi, Lidl etc. are large German super-low price discounters. They're more common in, guess, Europe. As far as I know they've overtaken in the UK as the best rated cheap grocery discounters already and they're also (fortunately!) everywhere here in Spain and elsewhere.
I only knew one Aldi near Chicago in the US and it was quite crappy so I can't say about the quality of Aldi in the states in general.
What's good about Aldi (at least here in Europe) is that they are a discounter who constantly has high quality but cheap, store/off-brand etc. stuff which also often gets the best ratings in consumer tests.
They also have seasonal stuff (like Lidl etc.) where you can sometimes get good deals on the weirdest stuff, ranging from PCs to mattresses, bikes, home theater systems, plants, whatever etc. but you need to be quick because that stuff is only available for a short time. There is even an entire line of ALDI PCs and Notebooks, their brand "Medion" which are actually decent.
I heard that once Walmart tried to establish itself in the European (German?) market but couldn't compete with the many ultra-cheap grocery discounters here.
Yeah, no friendly service, no help bagging and "go grab a card-box box from the pile to carry your stuff"...sounds like ALDI to me