I talked about the Willis Ave. Bridge way back in October I think it must have been, right after they opened the new bridge, just before the New York Marathon. At that time, the old and new bridges stood side by side, with the new bridge taking the vehicles across the Harlem River, and the old bridge still taking pedestrians across.
Since then, the old bridge has been dismantled and the pedestrians now get to cross on the new, wide walkway of the new brown bridge, and it's actually quite a nice way to go (see pic above). But there are a couple items to note.
Construction crews are still removing the last remains of the old bridge approaches on both sides, so the pedestrian entrances are a bit out of the way. In Manhattan, the entrance is accessed from 126th St. and 1st Ave., like the temporary entrance to the old bridge, but you have to walk on the ground further, going under an old roadway, before climbing the stairs to the bridge. In the Bronx, access can still be had from the south side of Brucker Blvd. at Willis Ave., but you really have to walk way out of the way before crossing over a temporary overpass to get to the bridge. But it can be done!
The ohter interesting item is that the two spans of the old bridge are still sitting in the river just north of the bridge. (The old bridge had a shorter swing span and one fixed truss span. The new bridge just has the longer swing span.) I do not know what they are planning to do with them. Turn them into scrap metal I suppose, but until then they're on display in the Harlem River. All of this, by the way, is actually accurate as of about a week and a half ago, but I doubt anything has changed since then.