Hello D-Nice, well lets take this question from a first-hand point of view, being living in Jamaica for 20 years, I have had the uttermost experience of knowing about the safety of Jamaica. Lets make it clear that Jamaica is indeed one of the safest places you can be. You are embrased by warm and friendly people, who will indeed look out for you, and will make sure that your visit to Jamaica is as enjoyable and memorable as it gets. However, within the basket, there is a rotten egg, and sadly, Jamaica is not excluded from this view.
Depends on where you go, Jamaica can be safe or unsafe. If you flight and vacation takes you to the north coast, then that is a big bet of safety - the government spends a lot of money, time, and effort to accomodate the tourists while ensuring that security is at its maximum. The hotels are extremely safe, whether in Montego Bay, Negril, or even southside in Kingston. Tourists are given first hand preference of travel, and will always be secured by the tour guides and drivers, et al. From hotel to the airport, it is the same approach, and of course, our airports are safe (so safe, that after the incident of 9/11, Air Jamaica was the first international airline to enter the United States.... from Kingston to Miami Intl.).
However,. as glamourous as Jamaican life is along the coast line, NEVER BE ISOLATED, especially if you look like and talk like and act like a typical tourist. Let me pose an example - I am a fair skin person myself, and I tend to dress very proper, even when on the road, going to class, or to a function. While on the road, some men will give a pass, wanting to beg for money. Whilst letting them know that I am a Jamaican (thus expected to be poor too), they insist that I am some European or Atlantic American mixed person. Of course, to defend myself, I have to introduce my Patois, or else. Alway walk in groups if you are going into the town areas. If in the suburbs, you may take a chance, but my advice is to stay within the tourist designated areas - and you will be fine.
Now, Montego Bay, Negril, Ocho Rios, etc are swarmed with tourists, and so you will be fine. Going inland, just be on your guards. Now on the Southside, Tourism is not as developed as in the Northside - however we do have eco-tourism. Most of the crimes take place on the southside, especially in areas that are isolated and non-densely populated. Kingston, however, which do have the inner-cities, is not so bad either. Some inner-cities are really good actually, and you can walk any time of the day, and some times of the night. New Kingston, Jamaica's little CBD is one of those urban safe places, with hotels, banks, malls, movie places, travel agencies, hotels, parks, recreational facities - you name it. Security is often times at its peak (although I must warn you about prostitutes and "un-straight" men who plauge the area at nights - and can be barefaced about their personality in the day too). Downtown is one little call for concern - again, go in groups, or, preferable, go with a yardie-born Jamaican who you know and/or can trust, or else.
Jamaica can be a dangerous place, but its mostly safe. You just have to know where you are going, what you are doing, and at what time you are staying - these factors can determine first hand your safety.
Hope you take this view from a 'native' himself. And don't fret, Jamaica is really a cool country. Like we say, "Come to Jamaica and feel alright". :)