It helps a child to interact well, with parent and others.
Later it will become the norm, so brilliant idea.Something that will be a lasting memory too.The sooner children are introduced to 'outings', the more they like them.
Definitely - the kids love them and it is quite fun to see how different cafes serve them (rainbow sprinkles, marshmallows, chocolate sprinkles). I reckon the one in your photo looks really rather good.
I don't tend to buy them, but at places where they are free for kids with every adult drink purchased I'd grab one for my son. Otherwise he's happy with water. I think they're cute and a nice treat for kids, but some places charge around $3 for them which is a bit steep for a drop of milk.