I've been seeing this stuff everywhere these days, and recently I've taken to buying it and experimenting with using it as pizza sauce.
What passata amounts to is strained fresh tomatoes, of roughly the same consistency as canned tomato sauce, but of vastly superior quality. "Passata" is a protected designation; it must come from Italy, and be made according to some State-mandated quality-control specs (which may account for how every brand I've tried thus far tastes and behaves very similarly). Finally, it is always sold in vacuum-sealed bottles of about 680-720 ml.
I find that this stuff tends to be too soft and mild for a heavily topped pizza; it gets overwhelmed when buried under toppings. But it works beautifully for Roman-style pizza rossa, Philadelphia/Montreal tomato pie, and, I'll guess, any other cheeseless style and/or style in which sauce goes on top. Very convenient, too; just pour dollops over the dough surface, spread with spoon or fingers, dust with whatever type of spices, and you're all set. Finally, it's very economical compared to tinned tomatoes, since 100% of it is usable tomato product. Passata is now a stock item in my pantry.