In the example for dragging and dropping features onto a map, it says it supports CSV, images, map and feature services. It was unclear to me how you might drag a map service, but I tried dragging it from a window of my rest services and it worked just fine. Very cool - I had no idea that was part of the functionality. I'm sure this is generally overlooked, since the example is based on a CSV file.
Mostly I have map services that I load as featureLayers, as opposed to authoring featureservices. In the code, it looks like it generates a generic infoTemplate, but when I click on the map, I don't get any information. Am I misunderstanding how that should work? I think my map service is getting loading as a featureLayer, but maybe not.
Drag and drop to display data | ArcGIS API for JavaScript
