Of course almost any event of this type is positive. NYC now closes 7 miles of streets, including Park Avenue from the Brooklyn Bridge to Central Park on 3 summer Saturdays.
Bogota, the originator of the "Ciclovia" closes over 120 kilometers of to cars once a week, in events that bring more than 2 million people onto the streets! (Medellin & Cali also have large events)
Mexico City closes over 60 kilometers of streets.
Los Angeles closes miles of streets including a big chunk of Wilshire Boulevard, 3 times a year.
"Atlanta opens several miles of streets throughout the year for Atlanta Streets Alive. On April 20 the festival will close a 2.7-mile loop in the West End, and in May the city's Peachtree Street will be closed from Downtown to Midtown."
Paris's streets along "the Seine are not only banned to cars, they are also transformed into "plages" or beaches, which include sand, umbrellas, beach chairs, and actual temporary pools. The plages are installed for July and August."Nothing against what Pittsburgh did but hopefully the future events will be more worthy of the name. An event next year may close 3-4 miles of Pittsburgh streets to cars.
A few links about Open Streets, Ciclovia movement.
The Rise of Open Streets
Ditch Your Car And Grab a Bike For These 9 Open Streets Festivals
Open Streets Coming To Pittsburgh