I live in London they brought it in and it's been ok overall. It doesn't stop congestion but reduces it a bit. For commuters it's probably a bit better as they mostly use the train/bus etc and benefit from less traffic. For workmen needing to deliver and fix things it's a bit of a pain. For me living in the center I'd probably take the plus of less traffic over the minus of getting a plumber to visit being expensive.
Re the tax grab - yeah but they have to get tax money from somewhere to pay for services and the like.