Ass Juice. You kind of have to have it at least once. It's like a strange bar rite of passage. Even Anthony Bourdain tried it.
I spent some time working in Vegas, and the Double Down was walking distance (read: big trouble) from our digs. Our group was here almost every night, and had a killer time.
Not typical Vegas, which makes it kick ass. A dive bar at it's best.
Good music, good beer, pool table, and a rowdy crowd. What's not to like?