I have been to Cusco 9 times over the past ten years and each time found Jack's to be a little less attractive. It is the breakfast menu that keeps bringing me back and then I think there has to be a reason why there are always crowds of gringos hanging out the front door. However, I've come to the conclusion that either they are all reading old travel guides that tout Jack's as the only place with an American-style breakfast or they are travel weary and want a taste of home so bad they don't care about quality. I was there about two weeks ago for a "Gordo" (a "Fat One") which includes juice, bacon, sausage, eggs, home fries and toast. Well, the bacon was two thick, hard pieces of meat about the shape of a No. 2 pencil, the sausages were the color of plum and tasted like solidified smoke (probably canned), the eggs were runny, though I had requested "over easy" and the home fries were just so-so; not much to be said about toast - good or bad. I don't remember if the coffee was included in the price, but the cup was awfully small (4 oz tops). All told, it cost me about USD 10.00. I get a better deal at Denny's any day. The service was less than stellar, I got the feeling as a solo traveler that they wanted me out as soon as possible so they could seat four people at my table. That particular aspect has been true at Jack's for as long as I can remember. Definitely thumbs down in 2012 and my last visit to this particular establishment.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.