I remember being attracted to it by the frankly gorgeous pastel artwork on the box set. The artwork does mostly match the tone of the show, and the sound track is also very pretty. The fascinating video clip for the closing track Under The Blue Sky is one of the extras (watch for the counterclock in the linked clip).
Someday's Dreamers is an urban fantasy of sorts with mages running about in modern day Tokyo, and subject to modern day bureaucracy. So the main character is a 17 year old apprentice mage Yume Kikuchi who has come to Tokyo from the country to complete her training and be certified as a master mage.
The story has been quite tightly adapted from a manga, and I feel it was too tightly adapted. The episodes in the middle disc feel particularly forced in their resolutions, and lack emotional resonance as a result.
In contrast the final story arc flows a lot more naturally over the last three episodes.
Someday's Dreamers is a pleasant enough coming of age story, with a slice of life feel, but not much more than that. Recommended for light viewing, and easy listening. :)