Pizzeria Defina is not bad. I had not eaten in the Roncesvalles area in eons so I was enthused about checking this place out with my pizza-obsessed friend the other night and it was decent. I read some not-so-great reviews and wasn't sure what to expect but apart from the pancetta missing from my Roncy pizza ($16; Neapolitan crust--I like that they give you the option of Napolese or Roman crust), which had a nice amount of crispy-edged guanciale throughout, and the burrata ($12) being a big disappointment, it was alright overall and this had a lot to do with the great service and lack of pretension. Even without the pancetta, my pizza was pretty good but I'm sure it could have been that much better in a way that only pancetta can improve things. (I love you, pancetta!) Be sure to ask for the spicy oil with your pizza.
My friend ordered the Diavola and I could tell she wasn't nuts about it but we still ate every last bite. I only wish the burrata would have been better. It was a small piece that came surrounded with minced caramelized onions, a drizzle of olive oil and a little scoop of some tomato-y sauce. I guess the memories of Campagnolo's burrata are still alive and well and have set the standard for every burrata that follows. Kind of like the one that got away...
If you're in the Roncesvalles area, Defina is worth a try. It's laid back with a lot of locals and families with kids. They also have a list of cocktails you might want to try (we didn't), or you can always hit up one of the nearby bars.