So they're all happy that they go on a huge shopping spree (thanks to Homer), and then they're mad at him because he gets a little something for himself?
What's the big deal with buying a tree? Can't he cut one down like he did in the Christmas Special way back in 1989?
That's the point: Homer promised the family an excellent tree. However, because of Homer's idiotic greed, he spent most of the money on a $500 gift for himself and instead of the good tree that he promised, Homer bought a truly pathetic tree.
Beyond the Christmas thing it was just another retread plot, i.e. Homer is in some way insensitive, and then he overcompensates. There were a few nice isolated gags, though.
I actually laughed out loud when Grandpa Simpson was standing outside the window and Homer threw his shoe at the wall above the window, which caused a bunch of snow to be dislodged from the roof and fall on Abe. The rest of the show would have been a "B", but the part where Homer decided to take everyone's presents was where the ep took a downturn. It's not like Homer to think people would be happier without presents, not to believe Lisa on such things. I did think SLH was cute as the Grinch's dog, though.