We visited Omar Cafe due to the reviews on Happy Cow... and we were very disappointed, because we found it to be a typical tourist rip off with low quality and overpriced food!
We asked to sit upstairs on the roof terrace to enjoy the great view on Hagia Sophia and the Blue Mosque. The staff (friendly but pushy) allowed us only under the condition to eat something up there. So we did. The food we ordered was not tasty, organic or anything like that, but greasy and of minor quality. For this, the price was too high.
We did not return to Omar´s during our visit. I guess the vegan/ vegetarian place to be is by the Galata Tower where we found good place to eat.Pros: great view, friendly staff
Cons: overpriced, low quality food, very touristic