Guy Fieri has a few restaurants in Las Vegas. Recently I had a chance to check out one of his non-Vegas locations - Guy's Baltimore Kitchen at Horseshoe Baltimore.
I'm guessing Guy Fieri's Vegas Kitchen and Bar is pretty similar to the Baltimore version. The appetizer I had is a Baltimore exclusive though, the Maryland Crab Fondue which was excellent.
For my entree I wasn't too adventurous and just had a burger. It was mediocre at best, and overpriced as expected. I even think the waiter messed up my order as the burger I got had slightly different toppings as the one I ordered.
So Guy's Baltimore Kitchen was pretty predictable in my experience. Expensive, perfectly fine bar food. The Maryland Crab Fondue was really good though, and I would consider a return trip just to order that again.