I've been to Vegas my fair share since I turned 21 and never even knew about Holsteins! I gave it a try and it was beyond delicious!
I got the truffle lobster mac and cheese and half of the salmon burger. The burgers are so big and filling even though they don't look that big. My friend also got the billionaire burger which has foie gras and kobe beef with truffle mayo!!! the foie gras piece was a good size considering the burger was fairly expensive. They said it was really good as well.
Service was good and prompt. Although the waiter at the table next to mine kept dropping water glasses causing loud noises throughout the dinner... HOPEFULLY he didn't get fired :/
The only bad thing was that they didn't allow one of my friends to bring in his Fat Tuesday which I can understand, but still somewhat of an annoyance!