I watched Casino yesterday night and I really liked it. I did get a little bored at some time, so I think it could be a little smaller.
About comparing it to GoodFellas, I believe it is unfair. GoodFellas is a classic and Casino is an attempt to make another film as good as Goodfellas. that is not bad, Scorsese and De Niro can do anything they want to, but that's how it feels for me. And it is still very very good