Artbooks and their revealing details

I really only started my Yasuomi Umetsu collection, with his "Artworks" book. It's an amazing piece that everyone that likes Mr Umetsu's artwork, should own. I own other artbooks, from other artists, but this one surely takes the top spot, in my artbook collection, due to its exquisite artwork. But given its generic nature (it features original artwork, from almost every show/game, Mr Umetsu worked on), we don't get too many details on those specific shows.
For that, obviously, you need the artbook of the show itself and in it, we'll find some interesting details. Among them, there's the characters age and measurements - waist, hip, bust size (if applicable), weight, height, etc - but also, their favorite color and food. The "Yellow Star" artbook, contains all this info and more, about Ayana (the main female character), which I found very interesting. They don't just create a character for the show. They also give it a personality, besides what we can gather from the Episode/OVA/Movie itself and this is very good IMO. With this info, one might get attached to that character, even more so than we would if we didn't know about it. I guess it means that the character is not limited, to that specific show, to exist anymore.
In the "Mezzo Perfect File" book there's also a lot about the characters, especially Mikura, but I don't remember it being so specific, as the "Yellow Star" book was. As I recall, the only book, that doesn't feature all that much info about their characters, is the "A Kite" one. At least I only remember it mentioning Sawa's age (in both young and older form) and that's it, But I'll have to check it again, to be sure :)
All in all, I like this approach. The characters are not only detailed visually, but also personally. They are still animated of course, but it gives them much more depth. They are not just a bunch of colored drawings :)
Any thoughts about this ? Please share!