I would give this place 4.5 stars if I could.
Burger Bar is a really cool set up and a nice change up when it comes to upscale burger joints-you build your own burger, starting with meat, then going bun and toppings (of which there are a lot)
I went for a kobe burger with some cheese on a ciabatta bun-a burger you can't find much elsewhere, and man oh man was it good. The kobe beef was melt in your mouth perfect, and the bun was delicious.
Our server was great too, as were the hostesses. You can't make reservations here, but you can call 15 minutes ahead to get on the list (which isn't a bad idea)
I'll definitely be back the next time I'm in Vegas.