So many people get stuck on the shipping, which to me is incidental where HP is concerned, or the nameing of the kids, which well... they're wizards, all wizards suck at naming their kids, just look at all the rest of the names in the book for crying out loud.
But all those people nagging and nagging and nagging about the sentimentality and stuff seem to be people who haven't even bothered to read the epilogue, because it is essential.
In the first book, Hagrid almost instantly fills Harry with prejudices against Slytherin. It's in big part because of what Hagrid tells him about Slytherin that Harry ends up in Gryffindor. (and don't tell me Dumbledore didn't have a clue that this would happen, because I'm pretty sure he knows Hagrid well enough to know his opinion on matters)
Yet in that last scene, we see a moment where Harry could have filled his sons head with the same petty prejudices that he went in with, and he doesn't. We're shown that Harry has grown, has matured, has become a more forgiving man who can see beyond labels and look at people and see them for themselves.
He can in full honesty tell his son, "Then Slytherin house will have gained an excellent student, won't it? It doesn't matter to us Al."
Read those words "it doesn't matter", compared to Ron's joking to Rose, compared to Hagrid's words to Harry...
Harry releases his son from the chains of fear and dividedness. He tells his son about Snape, the man his son was named after and gives him a glimpse of understanding of Slytherin.
And I love Rowlings for doing that, for giving us an adult Harry who has truly come full circle and has become a man to be proud of.
Who cares that Harry ended up marrying Ginny, that Ron married Hermione, that's almost incidental in nature. It doesn't matter.
What matters is that Harry has become an adult.
And that is why I love the epilogue, no matter how schmoopy or sentimental it is.