Here is a negative aspect: Although it seems very hard to find up to date cost figures for the NZ filter, according to the Techliberty web site, in 2010 $150,000 was budgeted for the software (I guess you are on to a good thing there) plus $2,000 a month for the connection. This does not include added costs of employee time, hardware and other items. And all of it in spite of the admission by DIA that it probably doesn't actually achieve much. I wonder how many abused children could be fed and clothed for that $150,000+ ? Or how many extra police officers rooting out the sources of this evil?
Just in case you got lost in the details, here again are the positive and negative aspects you say you are interested in:
Positive
- creates a few jobs
- gives people a false sense of security
- makes people think something is actually being done about the problem
- wins votes
Negative
- doesn't work
- waste of money
- opens door to widespread government surveillance
- destroys personal privacy
- takes responsibility away from parents so they can shrug and think the State will take care of it, like so many other things
- easy to circumvent (even a child can do it)
- facilitates more child porn by shifting the focus to a fake issue
- acts as a child porn site finder
- encourages people to think more and better government intervention is an answer to anything, instead of encouraging them to find real answers
- more things than there is room to list