I've had Middle Eastern fast food in Germany (doners, yufkas) and in Istanbul, some good, some mediocre. The Halal guys' food comes very close to the best of those. (The best yufkas I've ever had: from City Imbiss, Herrenberg, Germany, one of a small chain of imbisses. And unlike some imbibes, this one has seating, which is heaven sent when it's snowing or raining.)
First tried the Halal Guys fare about three years ago. I'm a little wary of eating street vendor food for sanitation reasons. However, ever since my brother-in-law, the brave soul, bought a plate of food from the Halal guys, raved about it and best of all, did not get sick, I have indulged in a beef, lamb, or chicken plate from them on every visit to Manhattan. (I go there once a year.) It's always good. Love the white sauce they use. It's probably very high in fat calories but after walking for miles in Manhattan, I feel I deserve a treat.
Best of all, it's really inexpensive ("cheap" has a negative connotation).
BTW, I've stuck with this one on 6th/53rd, Hilton Hotel side of 6th.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.