I think it's worth it. If two people staying near the Pantheon go out of their hotel for their morning coffee (which they generally should), it will cost about two euros, more than the cost of this app. Then at night they'll likely be told by their concierge to eat at a restaurant on Via Pietra between Via del Corso and the Fountain of Trevi, or at a restaurant in front of the Pantheon itself, and spend seventy five to one hundred euros eating junk at a tourist trap.

For $1.99 they would have known to walk a few blocks the other way and eat at Armando Al Pantheon, where they can eat like Cesar for the same price. If you only have 7 days in Rome, consider it as insurance to avoid wasting a day where a meal is an important part of it. If you have less days to spend in Rome then you have less to waste, and avoiding bad meals is even more important. Never trust your concierge.

The Colosseum, the Forum, Piazza Navona, Spanish Steps, and all tourist sites are full of tourist trap restaurants. People don't worry about spending 4 euros for a liter of bottled water in those restaurants. Why worry about spending $1.99 to know how to avoid those places and eat better food where the water is 1.5 euros for a liter?