I have to agree this didn't deserve the mature rating. And too felt this fell flat.Spoiler alert:
Having read the manga as well as watched the series I have to say both sides are a bit of a let down for someone who created the Fullmetal series. Anime expanded some of the backstories of some of the characters. However, it seemed to be at the expense of the others. I liked hw Koyo and Rinmei got more than the bit parts they were assigned in the manga but dislike how the anime took away Laila's power and made her a weak tag along. In the manga she was the one to take out Shimei for good and she had a special power all her own that aided the stars. Ryuko's betrayal in the manga seemed sudden and never was explained, though he swapped back pretty quick as well. So I like the anime depiction of his betrayal and trying to hold through his beliefs until he realized what his father is really planning. Shokaku I did not like in the anime. He was weak and incredibly foolish while in the manga, not only is he not dying, he is shrewd and seems to be following the path of his own plans. He's also pretty cold which made him a wild card where you didn't expect it.Overall both had their pluses and minuses. I just wish the creator had taken the time to actually develope the story to his own tastes instead of just drawing out a shallow depiction of the legend.

Spoiler alert.This anime was in so many words; decent.
Not the best, not the worst.
DID NOT LIKE: how the last 4 episodes of this series were basically the same thing. Seems as tho they stretched it out about two episodes too long.
DID NOT LIKE: the fact that the main character taitso did not have a romance part. Like really, isnt that what makes a good manga series? when at the end, the main character pOWNz the bad guy and gets the girl? yeah, this series didnt have that.
DID NOT LIKE: His resolve at the end of the movie " to live in a land where everyone can live with a smile" ? WOWWW.. Give me a break. Is that the best that they could come up with?
DID NOT LIKE: How I had to create an account just to watch this and I think the closest it ever got to being over rated-g was in the 1st episode when shemei cut lailas' (taitsos sister) shirt. Lastly ; WHERE WAS THE CATACLYSMIC EVENT!?!? It showed taitso getting pulverized and than out of nowhere he goes super saiyan and punches right thru a 'god'? I mean keiro consumed a sword with his pecs.. Like really.. Smh. The 2 stars that i rated stand for thumbs, and they are wayyy down. Make something better.

Spoiler Alert: stop reading if you haven't watched the episode.Overall I enjoyed this series, mainly due to the art of Hiromu Arakawa in designing the characters.But coming from the author of Full Metal Alchemist, this series lacked real emotional depth, had little real character development and the plot was comparatively simplistic.The ending was a let-down. It all ends w/ a single punch. And not much of a punch at that, what with all the build up throughout the episodes that the confrontation between the Alkaid and the Dubhe would be an EARTH SHATTERING CATACLYSM.