I was in Vegas last weekend and ended up at Burger Bar twice.. I didn't plan on going here so much, it just happened. I went my first night, got a burger and threw an egg on it - it was delicious. Went back the next night, did the same thing. They cook em to order, the fries are good and it's about what you'll spend at any other place in Vegas.
If you're in Vegas, you should probably roll on over here and make it your 2nd burger of the weekend (after an in n out, of course).