Stephen Georg’s review published on Letterboxd :
Having watched Vacation and European Vacation a few months earlier, next up was Christmas Vacation, and just in time for the holidays!
The formula is largely unchanged from the previous two films: Chevy Chase plays Clark, a happy-go-lucky idiot father who seems to wreck everything he touches. The humor is similar, and anyone who enjoyed the earlier films will definitely get a kick out of this one, too.
I find it odd that the children seem younger in this one, when it happens chronologically after European Vacation. Of course, the children are played by different people in every film, but it's really weird to see them shrink so much.
Chevy is great as always and carries the film, but Eddie (played by Randy Quaid) shows up about halfway through the film as the hillbilly no-manners cousin and adds a lot as well. The funniest scenes are when the house is full of relatives, all making Clark's life a living hell in their own special way.
It's also worth noting that one of the most hilarious secondary characters, Aunt Bethany, was played by Mae Questel, better known as the voice of Betty Boop back in the 30s.
Overall I think I enjoyed this film slightly more than the previous two, but it's really close! Definitely one of the greatest (and funniest) holiday films ever made, and recommended.