We spent a week at the Hyatt just down the street. The hotel bar staff recommended it as a local institution so we tried it out. I had a beer there a couple times and found it very friendly. The first time we eat at Nyk's was great. The Belle Gueule Rousse beer was great and the hand battered Fish and Chips Rocked. I saw someone eating a burger and it looked large and good.
We went again a few days later during the the jazz fest. Everyone was just as friendly and again we sat on the street to people watch. I ordered the burger and my wife got the chicken burger. They were Okay, but not what I expected. The burger looked smaller, but was still good. My wife said her chicken burger was pretty flavorless.
For the most part I am going to chalk our second experience up to the craze of the jazz fest. If you have attended you'll understand. We sat down at 3:30pm by the time we left at 4:30 there were no seats to be had. The atmosphere and the friendliness of the staff make up for it. And there was never any pressure to vacate our table. I'd try it again in a heart beat. If you like good food, good people and rustic. This is the perfect place.