I work right next to one of the East Oxford jobs, and while as a cyclist I agree with the principle tbh it's a bloody shambles.
It's resulted in awful traffic in the few rat runs that are left, with all the fun that brings. Alternative infrastructure provision has been negative (sod all cycle network, lots of bus services withdrawn) and the whole thing has proven a nucleation point for bitter conflict within the community.
East Oxford is an odd mix of yoghurt-knitting middle class / middle age professionals floating around on cargo bikes, as well as emotionally immature, populist men of a certain age who won't be separated from their cars by the shadowy socialist megalomaniacs. Bollards are only present for half the time due to being nicked / chopped off / run over, while I've seen a couple of pretty visceral confrontations between those of opposing opinion...
Further... while the purpose of the LTNs is ostensibly to reduce the frequency of short urban car journeys, it seems they fail to realise the benefits this should bring due to longer, less direct, more congested routes taken by people continuing to use their cars out of necessity, defiance or absence of legitimate alternatives.
I also live in Oxford and you are right it is a complete shambles. If you want to get people out of cars then provide a proper safe cycling infrastructure and heavily subsidise public transport so people have an option. These policies always seem to be stick rather than carrot.