In Atlantic City this would be a solid 4 stars, believe it or not. However, compared to what's happening south of the Riviera on The Strip right now, meh.
There are a couple of things to note on the good side-
the slots are never crowded and neither are the table games
the crowd here is as unpretentious as you can get
the history of the resort is hard to match- Dino used to be a part owner and Liberace was the headliner here shortly after the doors opened for the first time. Frank Sinatra had one of the rooms in the Monte Carlo Tower remodeled to meet his tastes during one of his runs. There are a few exhibits of the heyday of the Riviera near the Monaco Tower including a great photo of Elvis and Jerry Lee Lewis onstage together.
rooms are cheap
Peppermill is right next door
On the bad side-
it's dated inside...from the way it's decorated to the way it's operated
unless you can appreciate "Old Vegas" you won't think you are getting the Vegas experience here
Some new developments are underway nearby which may force the Riv to update and upgrade in order to stay relevant. For now, they are firmly in the 70s & 80s in terms of style and it's not even good enough for hipster irony right now.