There have been huge advances made in the police in recent years. Prejudices based on class and race are well-documented, and a big effort is being made to move past them. It's really encouraging. Also encouraging is the drive to deal more sensitively with domestic abuse. There is a recognition that just as institutional racism exists despite the absence of racism in individual officers, institutional prejudice exists against victims of domestic abuse because the role of the police is not to examine the complex dynamics of human relationships but to establish whether a criminal act has taken place and who is responsible for it. This can lead to the victim feeling under question and in cases where a woman has physically defended herself can result in her also being arrested for assault.
Unfortunately, despite the police making all the right moves to deal with this, this has yet to trickle down effectively to all grass roots level officers, just as was the case when race was first taken to task (a process which is still ongoing of course, but has seen hugely significant improvements). It really is a case of luck as to whether the officer called to a DV scene will truly understand the dynamics at play in a DV situation or whether he/she holds the prevailing view in society that the woman is somehow complicit in her abuse and must have provoked it or is as bad as he is because she 'keeps going back' or 'gives as good as she gets'. This is improving all the time and I think there are more good officers than bad, but it has a long way to go. For women whose relationships are characterised by their ability to pick up on every subtle little nuance of body language, facial expression and throw-away comments, any police officer who has even a smidgeon of irritation/disbelief towards the victim will be glaringly obvious to them.
Generally, however, I'd say the police have made huge improvements. The main problem lies with the courts IMO. DV is still seen as a lesser crime in the way punishments are handed out. There is still a problem with sorting out injunctions etc unless the victim has either money or easily available legal aid (not likely, despite govt protestations to the contrary), and unless the victim can prove urgency, which isn't easy, they take time that the victim often doesn't have, meanwhile she is living under intolerable levels of stress and fear. Is it any wonder so many women go for an easier life and go back to their partners where all this stress will disappear (even though it's only until the next incident).
One of the biggest problem as far as I'm concerned, is the still persistent notion that DV offenders somehow have a problem that requires treatment rather than punishment, or that alcohol/substance abuse is the main problem and the offender wouldn't offend if they just stopped drinking/taking drugs. It plays into the myths perpetuated by abusers everywhere that abuse is something they can't help. Most of the current studies clearly demonstrate the opposite - that most abusers make a deliberate choice to use an abusive pattern of behaviour to control their victims. This is the reason why most of them manage to maintain normal relationships with others and at work. While there are, of course, thugs whose every relationship is characterised by violence, they are the minority.
Less than 5% of abusers successfully change, even with treatment. The most successful programmes are those that hold the perpetrators responsible and stop taking an anger-management approach. It is a constant source of frustation to me that this has not yet been taken on board, though the recent rash of high-profile deaths and subsequent criticism of how the police/courts deal with it may see this change.