This show is very very enjoyable to watch, especially if you are really bored at home, with nothing to do.
The first 13 episodes encompasses the story of Allison and her childhood friend Wil, and the second 13 episodes encompasses the story of Allison's daughter Lillia dn Trieze. This creates a pretty unique story, as the characters in the first reappear in the second. The story, however, is not really focused so much on the plot, as it is for the interactions between each character. The holes in the story also lowers its value.
The art isn't the "wow" kind, but it is good
enough for the story.
I liked the lively sounds in the show, and it makes a person feel happy (like the OP). It also has great suspense music at the serious scenes, and is pretty well placed along with the actions. The voices of the characters also match their archtype.
In the entire story, the one thing I found most desirable is the portrayal of the characters. Each character's past isn't explained much as it is very short, but their personalities are well defined, and you could infer how they became like that. Also, the main characters are pretty likable and the enemies are shown in a believable way.
The plot itself was very thin, but the show itself is well done. The conversations between characters and their adventures makes a person feel good. It is a very enjoyable series (albeit people who don't like adventure stories).
It is definitely worth watching (its a full days worth of anime (26x20)+2hours for food and toilet) and it is a good watch for a break from the more serious side of anime.