The only way to get a true answer to your question would be for you to call the police department and ask them. If you can give a competent Realtor a specific address, they should be able to give you an "off the record" read on that location.
01904 is traditionally the "best" part of town by many personal judgements. There are parts of 01902 that are also desireable to many such as the Diamond District. There are also parts of 01905 that are highly desireable and over time, much harder to buy a house in than either 01904 or 01902.
My personal definition of a "good" location is an area where everyone owns where they live. I believe that if you use that as a criteria, you'll get a reliable answer. 01904 is much more predominantly single family in nature than 01902 is. By definition you will find a much higher proportion of tenants in a multifamily area.
If you'd like to give me a specific location, I'd be glad to give you my impression.