Even though I'm quite naughty and do most of my shopping at the Commissary on the military installation (it's ridiculously convenient), I do also like to shop at the local stores, but I do try to limit myself because there are way too many verboten delicacies awaiting.
Here are some of the things that I like about German grocery stores/supermarkets when I do go:
-they have delicious things to eat and those things are missing a lot of the nasty additives, dyes, etc. that American foods have; the bread here is especially fantastisch
-yummies like gourmet bread and cheeses are so much cheaper (and tastier!) than they are in the US
-wine is also quite cheap (oh oh on this one!)
-one must bring one's own bags for groceries, though it is possible to buy bags at the store. Initially, this is an inconvenience, but it's soooo much better for the environment.
-one must bag one's own groceries (though there is a downside to this, too) so things are arranged exactly as one likes
-the cashiers aren't chatty. You'll pretty much get a "hallo," "would you like a receipt," and a "tschüß." The cashiers are efficient and this makes them even more so. Since I am usually incredibly grumpy while grocery shopping (which I hide and am pleasant enough outwardly, at least), I am happy not to try to make small talk in a language I don't really know yet while keep track of the unfamiliar bills and coins that are always inadvertently mixed in with my American money and getting ready to bag my items.
-I like that the cashiers get to sit at their tills. Yes, that doesn't really affect me directly, but I think it would be really NOT fun to have to stand all day at a till. I don't see any good reason for this. United States, I'm pointing at YOU. Sam Walton, you especially! (well, I know you're not here any more, but you get the point)
-the stores' "international" food sections are usually a good source of amusement; would you like 10 different kinds of American BBQ sauce, anyone?
What I don't enjoy so much about grocery stores in Germany:
-they're closed on Sundays and most aren't open super late (around here, at least, but thankfully the Rewe is open til 10 pm). This is more a result of stores in Germany not being open on Sundays in general.
-when I go, they're usually a madhouse of people desperately trying to get their shopping done. I need to be fair, though, and note that I shop on Saturdays or sometimes in the evenings. Of course it's going to be a madhouse when everyone else who works must try to get everything done at the same time.
-one must insert a deposit to use a cart. While I like the concept of this, I never feel like I will buy enough groceries to warrant digging out the euro required as deposit. At the end of the shopping experience, where my arms are laden with groceries that I then have to furiously try to bag after they've been scanned, I wish I had a cart.
-while I like the idea of being able to bag my own groceries, it's a horribly rushed affair where I'm trying to pay the cashier, speak German, and bag my groceries at the same time that the next customer is impatiently breathing hot breath down my neck like a raging bull. I should resolve this by just putting everything directly into my cart and pulling over after the transaction to bag things, but I don't buy more than would fit in my arms or in a basket so it only takes about an extra second to bag things. If I had more items I would definitely need to pull ahead.
-Oh lordy: I get into an utter panic when I enter the store that's impossible to leave unless one buys something, which is pretty much every single supermarket. Abandon hope if you enter and want to leave after not waiting in line to buy something. It's a sad, desperate thing because the only way to exit most stores is through narrow checkout lanes, which seems like a HUGE fire hazard to me. Don't even try leaving through the gates you entered; that will often set off an alarm. Instead, you have to "entschuldigung" your way through other grumpy shoppers and squish through the queue. It's not enjoyable for anyone involved.
I do like the German grocery stores. I just need to remember to never, never enter unless I plan to buy something ;)