There have been several Lego based movies and shows for children on television already. My son's love to watch them. Off the top of my head I can think of Ninjago and a Star Wars one. The name of the movie we watched last year is escaping me. Anyhow, I've found them to be well done and lots of fun.
I watched a few episode of Ninjago with my nephews. It was gawd awful. The CGI in the movie trailer looks light years better, hopefully the writing is, as well.