First, the restaurant is actually located in North Miami which is just south of Aventura. It's in a strip shopping center. It used to be in an actual diner about a mile or two south of the current location. The "new" location (they've been here a year or more now) is a bit smaller but food is still quite good.
I've eaten here for lunch 3 times over the last three months, usually with 4-5 other people. I can't say we've ever had a bad meal here. So many good things. The service is okay, food can sometime take a little longer to arrive since they're cooking everything to order. They often have a fresh fish of the day.
When you hear "diner" you think cheap food, but the food is very good and the prices are not cheap but are reasonable.