Adam Cook’s review published on Letterboxd :
Chris Sanders made one of the last great 2D animated Disney films in the shape of Lilo & Stitch. It looked like he was on course to make another equally quirky film for Disney with American Dog (later to be heavily altered and retitled, Bolt) yet Lasseter, now in control of all things animated at the house of mouse, was less keen on this vision and Sanders left for new pastures. What Disney has lost is certainly Dreamworks biggest gain yet as Sanders and co-director/writer DeBlois have produced the studios best film by a country mile.
The marketing campaign was terrible, the creature designs (excluding Toothless) aren't much better and it still has that cocky character trait all Dreamworks movies have but none of this really matters as the film has genuine heart. Typically the studio goes for laughs above anything else but Sanders and DeBlois have tried to create a story centred around the relationship between a boy and a dragon. Much like the relationship in Lilo & Stitch this is a touching, believable and funny pairing. Toothless is as wonderful a creation as you could hope for and he is both familiar (his mannerisms are very cat like) and otherworldly. This bond between man and beast is tested in a thrilling climactic set piece that has real peril and uses 3D brilliantly.
I just hope this is a sign of things to come from the studio rather than a one-off.