The last 15 minutes or so are heartwarming. Not gonna lie, I teared up a bit.
The elves, who all previously saw Arthur as nothing more than a clumsy, naive oaf that "would be more fitting in the South Pole" (an opinion that Arthur is secretly aware of), chanting his name while watching him ride Gwen's bicycle to her home to deliver it, with seconds to spare! And their voices fill the huge control room! *sniff*
Malcolm and company arrive to cover the sunlight for Arthur to deliver the gift before Gwen wakes up.
Arthur, Malcolm, and Steve seeing Gwen finding her gift and realizing Arthur should succeed his father.
Lets not forget this moment; after Arthur delivers Gwen's present, he falls in the snow on his way up to the S1 and gets snow on his face, and the wind puffs up his jacket. Gwen comes outside and catches a glimpse of him for a second before the S1 takes off. The fact that Arthur had become the new Santa makes it even more heartwarming.
When one elf scanned a child in the beginning, and got "56% Naughty," meaning no gifts in the stocking. An absolutely heartbroken look appeared on the elf's face, and he then promptly scanned himself, getting a "82% Nice" reading and thus letting him put presents in the naughty kid's stocking anyway.
Evie taking off for the first time in the film. The beautiful animation of flying over the North Pole and Grandsanta's speech about the tradition of taking the next Santa along for a ride brought a few tears to this troper's eyes.