It is revolting to see batons, dogs and fists used against protesters who are protesting wholly peacefully. The police deal with the protesters as if their protest were a crime per se, instead of a democratic right which the police should protect. How else can you understand the gratuitous police violence and the incarceration of hundreds of innocent people in street concentration pens for hours?
If someone breaks the law during a demonstration (e.g. committing vandalism, assaults or trespassing) they should be arrested not subject to on an on an on-the-spot beating. If they are not breaking the law they should be left in peace.
These police and policing tactics are incompatible with the norms of a democratic society.
(I find utterly vacuous the argument of the people who argue that because police in similar situations in some other countries might beat more people and more brutally that therefore people in London have nothing to complain about. By this criterion nothing can ever be wrong because there is always worse. It is hopeless and depressing argument.)