Most commentators have touted the safety benefits: commuters arriving from Fifth Avenue will no longer have to cross six lanes of dangerous traffic to get on the F. But the opening could have further reaching benefits as well.
Consider Fourth Avenue between Tenth and Eleventh streets: on the west side of the street, where the subway entrance has been open for decades, you have an array of shops: a cafe, a liquor store, a laundromat, hair salon, and real estate office. On the east side, you have empty storefronts. Hopefully, increased foot traffic can be the first step in a microeconomic revival.