Yes, Osaka does, in my opinion, have some of the best food in Japan (well, the parts I've been to so far).
As far as specific recommendations, it depends on how much money you want to spend. Traditionally, Osaka is known for its crab restaurants and fugu also, I believe. They are hard to miss, as many of them have huge, plastic fugu or crab signs outside, when walking down dotombori street.
However, the crab and fugu places tend to be a bit pricey.
On the streets on both the Namba shopping area and dotombori, there are many street food stalls, most of which sell Okonomiyaki or "Octopus Balls". They have chopped up octopus in a sort of potato pancake mixture. I'm not a huge fan of squid or octopus because it tends to be a bit chewy, but I make an exception when in Osaka, because it's always good there! This is a cheaper alternative to trying good food in Osaka!
Last year when we were there, Chinese food was becoming quite big in Osaka, and there were big lines to get into a few of them in the Namba area. We didn't try it, so I can't tell you how it was, but it looked good, and was available as sit-down or take-away from a street cart setup in front of the restaurant!
Heck, we even had some Okonomiyaki cooked fresh out of a street vending machine last year and it was pretty good!
Don't worry, you won't starve there, that's for sure.
For a quick snack, I always like a sort of bagel dog with seeded mustard, sold at Choco-cro, a chain cafe located in many locations throughout Japan.
We've also become big fans of a place called Ringer Hut, which has an Okinawan Oyster Sauce sort of chow-mein dish with crunchy fried noodles in it. Very warming on a cold day.
Anyway, that's a few non-specifics. I haven't had any food that wasn't good in Japan yet, so be adventurous, if it looks good, pop in and give it a try!