+1 for Strada
Zizzi is all right -- sort of what Pizza Express used to be
+1*** for La Porchetta -- very good but only for pizzas. And the 134 bus is dodgy to Muswell Hill at the moment.
I did not like Fire and Stone.
For sheer cheapness (and it's close to me) the ICCO in Goodge Street is the best value in Central London. Think student grub.