A Christmas episode isn't very idealistic for an 100th episode special episode but it worked in this case, because it managed to find it's angle other than just any other Christmas episode.
In homage of "The Christmas Carol" Cory gets to see how life would be if him & Topanga broke up. Topanga would oddly have three kids with the character she interacts the least with, Jack. I love how they stated they hardly know each other, I found that hysterical. This comes to Cory after he realizes that him and Topanga are too different, their holiday traditions are completely different, so he runs off on Christmas Eve. Meanwhile Jack & Shawn try to find a tradition together, in the end, it turns out to be ice skating, and that becomes their new tradition. All the interactions of all the characters were well developed and acted out amazingly. This episode really was a defining moment in Cory and Topanga's relationship. This is when they realized they wanted to spend the rest of their lives together, regardless of their differences. This is defined by a promise ring. All family comes together for Christmas, and Topanga is a part of the family. We have relationship issues, hilarious scenes, a holiday theme and an alternate universe, which pretty much is the formula for a perfect episode of Boy Meets World. Heartwarming 100th episode. Didn't disappoint.