O'Naturals is wonderful. Food is excellent, healthy, and very flavorful. I particularly recoommend their soups in the winter--the lentil soup is a miracle in a bowl.
Besides the food, the staff is very friendly, and the ambience is wonderful...they have floor to ceiling windows that let in so much natural light, you feel like you are outside. There is also outdoor seating in hip Davis Sq if you prefer.
The added bonus is free wireless internet and a few comfy couches. No one bothers you if you want to get cozy and do some work at O'Naturals...all in all, a great place!