I had the pleasure to have a dinner there with two friends of mine and spent a lovely evening in this restaurant.
The are where it is located, "il Pigneto", is one of my favourite places in Rome, full of cafés, wine bars, restaurants and I am happy to say that So What is a little gem among all these places.
Very easy going but full of character, not too big but comfortable. Before booking a table there I had a look at their website that is very well conceived and done, with all the useful information one may need and an English version.
The food is absolutely amazing, simple and fresh, well cooked and very well presented in good sized portions. Me and my friends all had a dish of the day (a side dish + two main courses), a glass of white wine and a bottle of red wine, and a sublime dessert (chantilly creme with a biscuit in the form of a bat).
The staff is polite and the service is quick and well organised.
I will definitely return there and recommend it to all - especially to non vegans!!