This is definitely an "it depends" situation. If you eat a lot of processed foods they have great deals. But imo they aren't better than Grocery Outlet, so I'd go there instead of wasting the gas if GO is closer. They have pretty good deals on produce, but sometimes their produce doesn't look very good. They have pretty good bulk food prices. Milk is always inexpensive ($2 a gallon), but you can usually find it on sale for that price or better at one of the four regular grocery chains. Juice, yogurt, margarine, and bakery items are all really cheap compared to the regular stores unless there is a good sale. Cheese, meat, and frozen foods (fruits, veggies, hamburger patties, ice cream) can be much cheaper here, but not cheaper than the best sales at the regular stores. Bread is still cheaper at the franz or orowheat outlets.
All that said, we got a circular in the mail a couple months ago for winco that had coupons to get free milk, bread, apple juice, and cereal plus we needed to do some regular shopping so that made the trip from north Everett to Marysville worth it for us.
The costco conundrum pertians to this type of store for me. If you aren't on a strict budget or highly disciplined you can end up buying more than you need or things you plain don't need because the price is just too good. So if you're disciplined about sticking to your list or are honest with yourself about what you need and will actually eat then it might be a good place to shop.