I think that the benefits of CCTV surveillance are outweighted by their downsides.
In reply to the points about 'if you've got nothing to hide, you've got nothing to worry about', would you feel the same if you were being watched directly? For example, imagine you're walking to the shops when you notice a policeman walking behind you, staring. You keep walking, and the policeman is still following. He goes into the shop after you, stands and watches you while you get your shopping, and then walks behind you as you go home. Personally, I would find this very unnerving, even while accepting that I'm less likely to get mugged if the policeman is nearby. It's an intrusion into my life which I haven't asked for.
I also suspect that CCTV cameras just move problems elsewhere. Someone going out wanting to break into a car, for example, might just go somewhere where they know that there aren't any cameras, rather than really be deterred from comitting a crime.
Also, CCTV cameras encourage us to mistrust each other. They imply that we need surveillance to prevent us all mugging each other, wheras surely there are better ways of encouraging a community to be cohesive.
There's also the inevitability of CCTV footage being misused. I'm sure that loads of bored security guards monitoring CCTV have zoomed in on womens' cleavage, laughed at people tripping over etc. I don't want to be turned into someone's amusement as I walk down the road, whether I know about it or not.
Perhaps a stronger argument is that CCTV cameras are 'the thin end of the wedge'. If we accept CCTV cameras, we are more likely to accept more intrusive forms of surveillance, such as ID cards, CCTV cameras with microphones, mosquito devices and so on.