I started with milk, but the marshmallows basically turn the milk into coffee creamer. Kinda cool if you're into that.
It was okay. It is flavored with coffee concentrate, and does contain a trivial amount of caffeine. But for me the marshmallows are completely not necessary. If you need milk and cream and sugar and caramel and whipped cream and cinnamon and sprinkles and junk in your coffee you'd like this. It works. But I like extra dark roast, and this definitely doesn't taste like that.
I'll try it again tomorrow. Maybe I'll get used to the sugar. Or pick the marshmallows out. We'll see.