Is this a Christmas film?

Yes and no. While it's not specifically centered around Christmas, it is framed by the holiday (it's Christmastime at both the beginning and closing of the story). I watch it each year during the holiday season (just finished watching it!), because, well, it's Christmas-y enough for me and I like the film overall.

I consider it to be one since it begins and ends at Christmas. It's a slow burn, but I love this movie during the holidays.

Not at all. Die Hard would be a better choice.