I find Christmas in Rome very pleasant and relaxing. There is less of the commercial pressure felt in Northern European cities, where it is all about buying and consuming. On Christmas day, most shops and bars are closed but people still stroll around town for their usual walk about. Even on St Peter’s square, where I made a point of going this year out of curiosity, the atmosphere was surprisingly relaxed. I expected it to be overcrowded and tense instead.
A little oddity in Rome around Christmas time: many shops lay out a red carpet on the pavement outside their windows. I haven’t seen that anywhere else.
On a more traditional note, there is also a timeless Christmas tree on the Pincio overlooking piazza del Popolo.