Having endured the grossness (is that a word?) of the Riviera Hotel and Casino's facilities and food service next door, my brother and I ventured to the Peppermill every morning for breakfast over the course of a five day conference we were attending.
The breakfast food is Denny's with a Vegas twist. The twist comes from the funky mirrored/neon interior and the short skirted waitresses. The food was more expensive than the breakfast buffet at the hotel next door, but the staff was friendlier and the food significantly better. If you are not staying in the northern end of the Strip it is not worth the effort to go out of your way for the Peppermill. If you happen to have the 'good' fortune to stay at the Riviera, plunk you food dollars at the Peppermill.