I'm like a kid in a candy store in this place! (And, to be fair, there is a decent amount of candy in the store.) This isn't *just* a grocery store, or *just* an international foods market - it is possibly bigger than a super-Walmart, and has food (and non-food items) from all over the world. Looking for an obscure ingredient? Chances are, JJ's has it. Each department is humongous, including the beer & wine section with selections from all over the world, produce section with many fruits/veggies I've never seen elsewhere (or even heard of in some cases!), a great natural foods section with plenty of vegan cheeses, yogurts, fake meats, etc. They also have natural non-food products, such as their amazing selection of essential oils. For the gluten-sensitive, there is a large selection of gluten-free products, in their own section.
Grab a map when you get there or you may get lost, and make sure you've got at least a couple hours so that you can take it all in. Make sure you check out the restrooms while you're there! Feel free to bring your omnivore friends & family with you, too - they have a large selection of meats & cheeses.
The only complaint I really have is that sometimes it can be difficult to find an item and price compare, because each country has its own section. I had grabbed a bag of raw cashews in the natural/organic section, and found a bigger and cheaper (per oz) bag while looking in the Indian section for some garam masala.
Cons: Hard to comparison shop