Katz's Deli had been featured on several shows and in several articles about NYC that I've seen and read, so when I found myself in NYC last September, I wanted to try it. It must be a tourist draw, though, because we asked someone working at an attraction across town what the best train to take was to get near it and he had never heard of Katz's. He said "you're going across town for a deli? There are delis on every corner," haha.
It is a no frills deli - cafeteria style - but the food is very good and the sandwiches are gigantic! You grab a tray and order at the counter or you can sit in the section where someone waits on you. My husband got a brisket sandwich, which was good, but my pastrami sandwich was excellent! We really could have just split a sandwich, they are that large. The counter staff was very friendly and helpful while we ordered, and gave us several different samples meats to try as well as several samples of pickles. This was a great feature because a sandwich will run you $16 or $17 USD, which is pretty pricey.
When you walk in the door they give you a ticket. When you order something they write on your ticket and you pay for everything at a counter at the door before you leave. If you lose your ticket there is a high penalty fee, so don't lose it!