Carnegie Deli is a totally overrated tourist trap in Midtown Manhattan. I think it's even appeared in a number of movies like the "Teenage Mutant Ninja Turtles." All the tourists who come to New York seem to know about it and are dying to go there along with the exceptionally lame Jekyll and Hyde. Carnegie Deli certainly offers a bit more than your typical Manhattan deli, but not by much.
I've only eaten there once, but I've done take out a number of times. To their credit, I will say that the extra large matzo ball soup is good and the pastrami and corned beef is not half bad either. Nevertheless, it's still overpriced and I'd suggest a trip down to Katz's Deli on the Lower East Side if you really want a good pastrami sandwich. But if you're from out of town and you're looking for something in the neighborhood, might as well stop in since it's conveniently located near all the midtown hotels. You'll pay tourist prices, but welcome to the Big Apple.