This was the first, and possibly the best, World Masterpiece Theater anime I've watched. If you have to watch just one WMT anime, this should be the #1 pick.
Story
Taking place in 19th century Europe, young Romeo is looking forward to a competition in his small village when they are visited by a man known as the "God of Death", who takes an interest in Romeo. After a series of events when Romeo's father refuses to sell him, in order to save his financially failing family, Romeo agrees to go with the God of Death to become a chimney sweep in Italy...even though kids are known never to return from the job.
Characters
Romeo - An honest, helpful, energetic eleven year old boy who puts others before himself. No matter the hardships he faces, he always tries to do the right thing and keep his word, as well as adjust as best as he can while keeping in mind those around him. He and Alfredo form a group of chimney sweep kids called the "Black Brothers" (due to the soot) so they won't get bullied by the local gang of kids, the "Wolves".
Piccolo - Romeo's "pet" ermine (who, for some reason, always has its winter coat) who sneaks into Romeo's pack when he departs and thus winds up in Italy with the boy. He's describec by Romeo as impish and a trickster, but his presence has helped in some situations.
Alfredo - The first boy Romeo meets on his way to Italy, and his first friend (who winds up becoming his best friend). He's book smart and loves to read, and possibly might even have an eidetic memory. He's a natural born leader, but still often defers to Romeo.
Luini - The God of Death, who buys children and sells them in Italy in order for them to work as chimney sweeps. He's a heartless and cruel man, who shows no qualms about his job.
Dante - Another friend who is slightly impulsive and has a big ego. Despite that, he's also helpful and often means well even if things don't always work out.
Of course, there are many more characters...but I feel that in anime like this, meeting the characters as the story progresses (rather than knowing ahead of time) is a much more immersive way; it also makes it more of a journey even though there is very little traveling.
Sound and Animation
Probably containing my favorite opening and ending songs of all of the WMT anime, the music matches perfectly with the scenes in the background as well. The song which the Black Brothers come up with and sing is also heartfelt and done well.
The animation is also well done. I don't recall it suffering from as many flashbacks to prior episodes like many other WMT anime have (if it did, I skipped through them and don't remember them). Really, the only issue I can recall having with the animation is Romeo's character design looking a little too feminine (sometimes, I forgot Romeo was a boy due to the design).
Overall
I rarely give very high ratings to anime, and the WMT anime are notorious for creeping along the "average" line (with the exception of a couple). This was the first WMT anime I saw, as stated above, and opened up my world to the other WMT anime due to how much I enjoyed this.
It had struggles, friendship, and more. Heartwarming and heartbreaking scenes, and a couple incidents which had me sobbing while others made me laugh.
There's an actual narrator, which might not be everyone's cup of tea; at times, it's as if the woman narrating is reading from the book it is based on (or just a book), and often gives away hints of what's to come. Even so, when the events hinted at do happen, it's still animated and acted in such a way that the narrator doesn't take away from the series.
I'm typically not a fan of an overall narrator, but in this case I felt like it worked very well. It felt like I was listening to a book in addition to watching an anime. Now, I'm no fan of audiobooks because I'm not an auditory learner, but it felt almost like a "story time" without being patronizing to the viewer.
As for age categories on this...I'd say that it's safe for most ages. Due to there being some child abuse and child labor in the series, I wouldn't recommend this for children younger than six. Parents who want to show this to their children (children under the age of 10) should probably watch it with their kids as well...mostly just to be able to explain some concepts that children that age might not completely grasp.
That said, it's an amazing journey of friendship and even morals and hope. There are a lot of messages of sticking together and teamwork, as well as a glimpse into what life was like in the 19th century.
There really isn't much else for me to say here without ruining or spoiling it, other than this anime is among the list of anime I highly recommend to others.
WMT reminds us that anime doesn't have to be "boobs and butts" to have interesting characters, immersive settings, and gripping plots. Romeo's Blue Sky, particularly, is a shining example of that.