Almost all of the "professional" critics gave this an unfair score because they didn't see it as anything past a toy commercial. That is wrong, you must see it as a show, and nothing else, in order to rate it. And of course Lego's main reason of making the series is to promote the sets so that they can get attention. But if that was so (it is only a toy commercial), then why is there such attention to detail that one might argue that there is too much detail?
Ninjago's story starts out basic, but as the show progresses, the plot starts to get very interesting, just like any other show. It combines interesting topics with Japanese and Chinese culture, so it isn't the same thing you've seen a million times. Characters are different, with unique drives and personalities.
A strong point for Ninjago is it's graphics. If you can, watch it in HD, and the details I was talking about will keep someone who is uneasy staying (Especially the spirits season). The characters are not shiny, as is assumed since they are minifigures, rather certain parts of the suits worn are (armor, badges, gold and silver decorations). It is the best looking 3D show on Cartoon Network. Also, the show might be based on the Lego sets, but the show itself actually has no Lego to be seen besides the characters.
The show is suitable for anyone apparently 7 and older, but there is still some uneasy moments, death, and light blood as well as small to large scratches are visible on characters (but it's almost unnoticeable).
On the topic of toy commercials, yes there are certain sets that can be seen in the show, but not all of them. For example, the largest Lego set in the season 5 wave is a huge temple, yet it is not seen in the show at all.
All in all, Ninjago is a brilliant show that honestly deserves no less than a 7/10, as anything less is most likely someone who has harshly branded the show as a giant toy commercial that is only watchable by kids.
