Well the filler episodes can be really funky, wrong or extremely disappointing. So compared to the MANGA should I consider episodes that aren't straight from the manga as "canon"?
The filler isn't in the manga, but it's canon for sure....And I like it because it adds depth to the cast of characters.....In the manga some of them are given a flashback on their life and never seen again....The filler helps flesh out relationships and make us care about them more and see why they're in Naruto's life. The movies can be considered canon too....As long as the stories don't contradict the manga it's okay to think of them as canon.