My 4-year-old loves this, but he does tend to copy the fights evil voices. We tried to stop him from watching but there is so much merchandising surrounding this show that it's impossible to avoid. Also his 8-year-old sister enjoys watching too and she's less affected by the negative stuff. There are positve messages too, using the forces of nature to combat evil, working together for a just cause, that kids can save the adult world.
Fine for the 1st grader and up to the 4th grade but it is very low-brow as far as content.
This is what they're talking about when they say, "Mindless Entertainment".