Personally, I'm of the opinion to criticize the restaurant to the manager in private, if you really want them to improve. Praise them in public. I don't think all restaurants, even those in business for ten years, are good. In fact, I think a couple are rather terrible, but you don't see people giving them praise as they do good restaurants. They will occasionally get a good review from the occasional patron, but mostly, if you don't hear or read good things about a restaurant, you might want to consider trying a place with raving reviews.
I will add that we all come from different places in life, with unique experiences, so I may have high expectations based on what I've heard about a restaurant, and receive avg service and food, so I may be disappointed. We must keep in mind that while there is such a thing as good and bad, expectations play an important role. If one comes from a small town like the place where I was raised, Captain D's was the only seafood place. Come down to south Walton and Elmo's may be fantastic! Try to be fair when judging these places and don't compare a great hole in the wall like Nick's in the Sticks to the elegant Fish Out of Water.
I want restaurants to improve, so keep letting the Mgr and owner know when they are not performing. If they ignore you, move on, and ignore them.