Here is a good introduction, it's one article of many out there, gives a good overview, and discusses what most people who study it think the issues are. This one is on the effectiveness of CompStat which is one of the prevailing theories. The others are gentrification, community policing ("broken windows"), and changing demographics--there are very few people who seriously credit gun policy with the reduction of crime in New York, other than politicians who are promoting it. You can see for yourself whether the author winds up supporting CompStat but reading the study overall will give you a good sense of the sorts of issues serious people consider.
http://www.scribd.com/doc/322928/Langan-rel
The drop in crime in New York has been remarkable enough, and NYC a large and important enough city, that the question has been
extensively studied. We do not need to take Bloomberg's word for this. I had expected that before you started yammering on about this topic that you would have bothered to google the basics--guess I was wrong.
I find discussions much more productive once everybody gets passed the dueling studies and statistical babble. If we can agree on what the facts are, and if we all understand what the prevailing theories are, and what the evidence for them is, then we can go on to talk intelligently about the topic.
At this moment you appear to be completely ignorant, other than you heard on CNN or somewhere that a guy named Bloomberg has an opinion that gun control is important.