I found out today from a friend that works at the movies that barely anyone goes to see HTTYD. He said that about like 2 to 6 people ever come to a showing.
This is pure speculation, but maybe it's because of the expectations of Avatar were drastically exceeded that for people that saw it before thought How to Train Your Dragon might be crap. I've seen Avatar already, and I think both of them are wonderful. Why choose a favorite when you can have two favorites?
It's wierd. How to Train Your Dragon was wonderful, and I think it fit with what the critics said about it, really:
"...Atmospheric, surprisingly detailed, and remarkably immersive. The overall use of 3D is exemplary." ~ Ain't it Cool News
"With its mix of action, comedy and heart it feels like no other animated film in recent years."
"It takes 3D animation to new heights and should keep audiences of all ages enthralled."
"Dreamworks has topped itself." ~Pete Hammond, Boxoffice Magazine
"It works enough miracles of 3D animation to charm your socks off." ~Peter Travers, Rolling Stone
I dunno about the socks part, but I do have to say that the emotional events between Hiccup and Toothless almost moved me to tears.
And the soundtrack... I simply adore what John Powell's composing has created. Even some of the music makes me cry.