Because it seems to be in a romantic movie. The view from the terrace is something magic! And you can go there in the winter too, because they give you warm blankets and warm lights so you can enjoy the terrace also with cold temperature. The personnel is very nice. I've been there for breakfast, happy hour, at night – it's always magic.
Because is lovely and cozy, not in the middle of the chaos of the city centre, but still very close to very attractive places like Ponte Pietra, Teatro Romano. You must have a drink on the terrace, enjoying the beautiful view of the hill with the Teatro Romano and Castel San Pietro, surrounded by the river's sound.
Go there at sunset to enjoy the light!