Very cool atmosphere and decent food, but a bit overpriced in my opinion.
Red Square is this hip restaurant in Mandalay Bay Casino - they are known for their vodka speciality drinks - I tried one of them (can't remember the drink but it was red with sugar rimmed all around it) but it tasted like it barely had any vodka in it.
We had the calamari (very good), tuna tartar (very tasty), and tomato salad for appetizer. My ahi tuna entree was tasty but rather ordinary - it did not make me say anything close to "wow, this is amazing!".
I do have to say that service was very responsive - one of my friends had her steak overcooked and they immediately took it back and shortly came out with another that was cooked as ordered.
Some other menu items that were interesting but we did not order were: a selection of different caviars and a monster lobster and fruit platter which I saw another table have.
Bottom line: hip, cool place for drinks (as long as they put enough vodka into them). Decent food but pricey - as long as your company is paying for it or you have a high roller buying you dinner, then you'll be fine.