The is fine, yes. The point is not just that they like snow generally, as a substance. The definite article makes the reference specific in the sense of indicating a particular facet of weather, a particular time of year, maybe also winter sports such as skiing and tobogganing.
I'd say "the" is optional. We don't know from this one sentence if they like specific snow or snow in general. We also don't know what they do on holiday - perhaps they just sit on a hotel balcony admiring snowy scenery - so they like snow, not the snow.