Casino is one of my all time favorite movies. The current state of the trope page seems to regard it as "not bad", which I consider truly unfortunate. I know that some people consider it an inferior follow-up to Goodfellas, and there's no denying the many similarities (De Niro and Pesci returning for similar roles, similar camera shots and angles, etc...). But while Goodfellas is a great film and hugely influential in the mobster movie genre, I've always liked Casino more and consider it the better movie. There are several reasons for this.
First, its a more visually appealing film. Goodfellas mostly takes place in the dirty suburbs of New York, while Casino takes place in the glittering den of depravity known as Las Vegas. This leads to many incredibly beautiful shots and scenes, and contributes to the film having a more epic, grandiose feel to it. There's plenty of gorgeous costumes as well, particularly the various coats and dresses of Ginger.
I also connect better with the characters in Casino in a way I don't always do with Henry and his friends in Goodfellas, and I care more about them. The performances are great; De Niro is perfect as the cool, intelligent but strangely vulnerable Ace Rothstein, and while Nicky Santoro is suspiciously similar to Tommy De Vito, Joe Pesci plays him so brilliantly that you forget that. Sharon Stone does a great job as the sociopathic, mooching Ginger, a character you just love to hate, and its captivating to see her evolve from a suave, stylish prostitute to a drugged-down, desperate wreck. James Woods has a very entertaining role as Lester Diamond, Ginger's sleazy pimp boyfriend.
A common criticism of the film is that its overly long, being nearly 3 hours. However, I'm entertained and captivated by it all the way through, and when a film manages to keep my interest on full strength that long, it says something about how brilliant it is.
In short, don't be fooled by people who simply call it a rehash of Goodfellas. To borrow a line form the Nostalgia Critic, if Goodfellas revolutionized the gangster genre, Casino perfected it. Its a spiritual successor that deserves to stand together with Goodfellas, and I invite anyone to see it.