I had heard really nice things about this store on Ravelry, and I have to say that it was really great. The store is really open with lots of light, and the yarn selection is really good. The prices were a smidgen high, but not a lot more than you would expect for something in downtown Chicago.
I ended up picking up some Lorna's Laces (dyed locally in the Chicago area) Shepherd Sock in Woodlawn, which is in Brubu-type colors and Cat Bordhi's New Pathways book.
And when we were leaving, someone pointed out the crocheted graffiti on a post in front of the store. How cool! Final verdict: Loopy Yarns is definitely worth a visit if you are in the area.