I have 2 Joann's within 5 miles of my house (literally, no exaggeration) and one is awful and the other (smaller, older) store is great. The ladies there know me, keep up on what I'm working on, and always cut an inch or two extra - more if the last cut was obviously wonky.
Quality wise...yes, I've learned to avoid the "calico" wall and head straight to the premium quilting fabric most of the time (though sometimes there is decent stuff over there on the calico wall; you just have to hunt for it). It can be bought on sale or with a coupon for what I consider to be quite reasonable prices. This is a pricey area; the few LQS in my area sell fabric for $12-$14 a yard and there's almost never a sale on anything I want! So by comparison, Joann's is a deal, even if you have to watch the sales vs. coupon prices.