We went to several in Pau. The latest was Pizza Napoli, Castle area.
We wanted to go to Etna opposite but it was full. Went there before and it was nice, even more when you can eat outside...
We waited a lot at the Napoli, the waiter was nice but I think he was alone... Not worth the money though. Very disappointing, the room downstairs is not agreable.
But if you have kids Pizzeria Del Arte in Quartier Libre is children friendly. High chairs, crayons... And it was ok.
Gusto, 1 rue du Hédas, Pau, 05.59.98.43.77. http://www.sortirapau.com/result_resto.php?id=87
Very small (book in advance!), you go down the steps to get there, it's comfy. And the food was nice, maybe a little expensive? Not very children friendly but with friends... I enjoyed it very much.
We have been to Pizza Napoli several times by ourselves and also with friends and have always been very satisfied with both the food and the service. Never sat downstairs though so cannot comment about that and probably not child friendly. A place we often choose when we cannot sit outside