IS SAN JUAN DANGEROUS?

I've been to 15 different countries alone and I plan to go to San Juan next month and I was wondering is it dangerous for a BLACK American and is it expensive. What is all there to do? What are great attractions and sights to see? Does it rain there a lot in March? For the most part are the people polite towards tourist or are they rude, shallow, & stuck up? Someone whose been there please answer. Thanks