TBH 2 of those stars are due more to my nostalgia for the city's market & the giant ferris wheel than to any quality of the movie. Plus I'm a longtime devotee of the waltz, and nobody does that like the Viennese
The cute American girl, the rich & handsome Viennese boy, the cute meet on a Christmas-bedecked cobblestone street...the script pretty much writes itself.
Actually it's a different male character she meets on the (beautifully decorated, cobblestoned) street, and only after she's been the traditional gauche New-Worlder and the rich Old-Austrian boy has been rude to her. Of course there is also a snooty scheming other woman.
After that, the script takes some pleasant detours on the way to the inevitable happy ending, among them that some extras had a point to their presence that was not all 'spoil the budding romance'. They seem like real people going about their own lives, with only occasional lapses into propping up the pretty heroine.
It's rare in holiday fare to allow secondary characters anything of a plot but the brother who brought Our Heroine to Vienna had his own minor storyline that eventually meshed with our heroine's, and a few bit players got callback moments in the final scene as well. Nice extra touches in a fairly nice and definitely pretty movie.
Settle in with your hot chocolate and your best dancing slippers, and prepare to be swept off your feet.