Here's a local's perspective on Kuromon Market based on our family's recommendation:
They call this "Osaka's Kitchen" for good reason - with about 150 shops under one covered stretch, it's where you'll find some of the freshest seafood and street food in the city. Our family says while Dotonbori gets all the tourist attention, this is where actual Osakans come to eat and shop.
What makes it special is how you can sample your way through Osaka's food culture - vendors grill fresh seafood right in front of you, serve up perfect takoyaki, or slice sashimi to order. Dating back to the Edo Period, it's maintained that traditional market atmosphere while adapting to serve ready-to-eat portions for visitors.
While it definitely gets crowded, our Osaka family says that's part of the experience. They recommend going hungry and ready to point at whatever looks good - many vendors are used to foreign visitors and make ordering easy. Just remember it's still a working market, so you'll need to watch out for local shoppers going about their business.