What a great threat! We just started shopping there a few months ago - I became a SAHM last year and after watching sales and still feeling like we could cut back on our groceries, we started shopping at Aldi's. I'll admit, I was a lot leery about shopping there because I like my food to taste good and I wasn't sure what to expect. However, it certainly didn't hurt to try new things.
We've had great luck with all their produce and scored some Tyson Steak Fingers that DH and DS loved.
Peanut Butter has been good
Veggie chips were surprisingly good
Cheese
Yogurt
Stuffing mix wasn't too bad
Cream of ___ soup mixed in well with our casseroles
Cereal: Choco Peanut Butter Spheres and Fruit Loops kinds (although the Fruity one seems to have a lot of dye that make other aspects of life interesting...

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Bread; white and wheat as well as hamburger buns. It also freezes well.
Fruit Snacks seem to go over well with DS
Pop - the grape soda is not too bad and DH is okay with the cola as well
So far I have not enjoyed the potato chips (I'm really picky about those anyway) or the frozen pizza, although we did not take time to doctor them up.
Glad to see some reviews so I can be more adventurous while shopping there and stretching our grocery dollars!! I've been a bit nervous about trying their meat as I'm picky about that too.