Ok it is a cool sight, but I felt bad for the lions. The habitat is inside the casino is pretty small. I read somewhere that the lions spend most of their time somewhere with 8.5 acres when they're not in the habitat, so maybe it's not so bad but still...
Who knows if that's actually true? I would hope so, but how do we really know?
http://www.mgmgrand.com/entertainment/lion-habitat.aspx