I can never decide what my opinion is on speed cameras. First and foremost they don't concern me personally because I don't break the speed limits. If more people accepted the rules and didn't break the speed limits, there would be no speed cameras as they would not be financially viable. As it is, it is ironically often those who dislike them the most that keep them operating thanks to their speeding.
There are certainly many places where speed cameras have made no difference whatsoever, sure, but there are also places where they have made a dangerous stretch of road safer, this is concrete fact (not just opinion), e.g. near me there is a piece of road that is deceptively bendy and dangerous that non-locals could be forgiven for underestimating. Since the introduction of a speed camera a couple of years ago, there have been no accidents, yet before the camera there was an accident once every few months due to someone underestimating the sharp bend and going too fast round it, putting their car in the hedge.
Speed limits: in an ideal world there would be no need for speed limits as everyone would drive sensibly even at high speed, but as it is I think the standard of driving is too low to just go and get rid of speed limits. I find speed limits help a lot when I am in a place I am not at all familiar with, as they can give an indication as to how bendy or hazardous a piece of road is. E.g. if you are on an open country road and there is suddenly a 30 or 40 limit, but no settlement, it is obvious that there must be some sharp bends or dangerous places, and this lower speed limit warns you and makes you more wary of what is up ahead.
Whatever your view on speed cameras, it is both the law and courtesy to respect the speed limits and you can have no complaints if caught. As has been mentioned before on here, the most stupid drivers of all are the once who get caught by a speed camera then go and moan about it. I know it's not for me to judge who should be driving and who shouldn't, but if you can't see numerous signs warning of cameras and then a bright yellow box and white lines dotted along the road, I'm not sure your eyesight is good enough for driving.
As someone who is a stickler for speed limits, I feel my life is a lot easier and less nervous than someone who routinely speeds. I don't have to lose sleep about if I was caught by that last camera, or if that car I overtook on the motorway at 100mph was an unmarked police car, or if I'm going to get an NIP in the post.