Don't let the line discourage you, as t moves pretty fast. Came here on a Friday night with about 10-15 people in front of me, but still was seated in roughly 15 minutes.
Steak 'n Shake is not a new rodeo for me, I'm used to the stand alone locations which have a little more appeal to them (windows, lower ceilings). The food was pretty much as consistent as I remember, I went with my go-to Frisco melt and banana shake. The shake was awesome as always and I gobbled up all of my shoe-string fries. I'm also impressed that the menu isn't given resort prices, as you can still get 4 combos for under $4 (recently named one of the best dining deals by Vegas Seven).
If the line wasn't as long, and not in the casino, this place would get 5-stars no problem.