They have fabulous prices... they're some of the cheapest around and their range and quality of supplies is very nice. The store isn't huge, but I believe they have most anything that someone would need. The staff there also seems to be pretty knowledgeable in helping you find the right supplies and tools you need. If you join their mailing list, you get some pretty great coupons too. You don't need a lot of money to shop here which is awesome because for me, going to an art supply store is like a kid (or myself!) in a candy shop
(The one drawback is parking... it's convenient that it's on the South Side, but parking can be an issue... but hey, there's always the bus :) and either way, it's still worth checking out)