Most of the barriers have been removed, but it depends on which council area you're in. The worst was a bridge which spiralled in to the middle, then spiralled out again the other side. Passable with a tandem, if you can wheel it on its rear wheel. Simply bonkers otherwise. The spiral arms (which cost umpteen GBP for an artist to create, along with two other bridges with horrid surfaces when wet, and difficult turns from ramps as well as kerbs up) have been hacked to half their length, so now it's just very awkward with a solo bike.
Mind you, the barrier at the bottom of a drop (both ways) in the middle of a metal surfaced bridge is a doozy.
Surfaces on the Wandle trail vary massively, with no more than about 200m of any type. There's sand, tarmac, gravel, macadam, brick paviors, mud etc etc.
And it's very hard to get through the Tooting section without a nettle sting.