We used to fly into all the islands (cargo delivery) and encountered good and bad everywhere. Most people are in the middle. Be polite and nice and generally they will be nice to you. If you go into a slum wearing a million dolars worth of camera gear don't be too surprised if you get it ripped off.
Dominica has some amazing scenery although a lot of it has to be hiked to. Nothing terribly serious but you want a pretty decent pair of hiking shoes before you attempt a treck in to some of the water falls.