Niederdorfstrasse is lined with restaurants and shops mainly, but not exclusively, aimed at tourists. That said, you have to expect that the restaurant will be a little overpriced, even in already pricey Zurich.
I was looking for a place to eat outside to enjoy the nice weather and couldn't venture too far away due to a meeting.Sitting outside on the alley off Niederdorfstrasse with a cool breeze was very nice. I had a Margherita Pizza (18CHF). It was fairly good, nothing outstanding. But, there are really far better places to eat with better value in Zurich, even in the touristy old town.