My girlfriend and I have recently returned from a long weekend at Annalisa & Leonardo's place and we couldn't recommend it highly enough. The apartment is in a brilliant location; within walking distance of all of the major sights. Being located right next to the Mercato Centrale; there are plenty of places to eat on your doorstep and Leonardo gave us some great suggestions for nearby food and drinks. Being only a short walk from the train station, this also made travelling in from Pisa airport very easy.
Annalisa & Leonardo were great hosts; meeting us on arrival and remaining easily contactable throughout our stay. We will certainly be back!