Halloween, opens the door for devs to do spin off stuff and change up the look of established characters as well personality chalking it up to some paranormal stuff.
Christmas is a close second as it's an opportunity for the dev to do stuff before the story line is ready but it's mostly what we would expect.
I really dislike holiday specials, I never download them (unless they are intentionally sewn into the game). 1. The developer wastes his resources, distracting from the main plot of the game, and these holiday episodes, as a rule, do not add anything to the game. 2. Cultural barrier. Halloween has not taken root in our country, and Christmas is in the background compared to New Year's Eve. Besides, Christmas is celebrated here by religious people, and practicing Christian believers are only 20% of the total population. March 8 (International Women's Day) is incomparably more popular here
So these Christmas-Halloween episodes are perceived as something completely alien, not touching any strings of the soul.
I think that Halloween has more content for sexy scenes, there is more variety with the costumes and how are the characters not only dressing but also behaving, on the other hand Christmas is more like reunion, so if it is a harem game, it is the perfect chance to reunite all characters and show true love.
I don't like them. They act as a "fantasy" of the MC and add nothing to the main story and sometimes they just skip all the build up to just make you fuck every woman out of the blue, when maybe in the main game you're not even at a kiss yet.
Can't say I've ever really seen a 'holiday special' that I enjoyed more than I would a regular update, so I guess I have to say no.
Granted, some devs are superhuman enough to put out both, but they're a minority. More frequently I'll see a Christmas update that's almost finished in time for Valentine's Day...