If you mean the Amagasaki location, yes, I'm aware of it, but have never been to it. I assume it's set up similar to the other Costco's in Japan I have been to (Tamasakai, Makuhari, and Kanazawa Seaside), which is very much like what you would find stateside. Pick up a shopping cart, show your card to enter, shop among the warehouse stacks for food, clothes, appliances, electronics, etc., check out, and have a Polish dog or slice of pizza with a self-service soda all while sitting on cheap plastic patio furniture--just like in the US! In fact, I believe all this stuff was shipped in from the US. If it wasn't for most of the other customers being Japanese, and many of the products Japanese, one would think they were in the US.

Whether it's worth it or not depends on what non-food items you're looking to purchase. While I could almost recommend visiting just for kicks, at 4,200 Yen for a year's membership, I can't really recommend it unless you actually are planning on using the membership.

The three Costco's I have been are in locations that are best reached by car. All three have ample parking. I can't speak for how easy it is to reach the Amagasaki location by public transportation. They do have a shipping service to ship your purchases back home (in Japan), but I've never used it as I have always gone by car.

Costco Japan English website