Just yesterday, I was discussing Ed Greenwood's old "Pages from the Mages" column in DRAGON magazine. Crusty old Elminster would explain the origins of a couple of spell-books from the Realms, and details the spells in them, with rough edges, aspects of the dwoemers that didn't work quite the way the originator had intended, and such. Even the "standard" spells in the books were sometimes variations (usually slightly deficient) off the standar PHB versions.
I'd been saying that I liked that, and it was one aspect of 3rd Edition I missed, and that (in my opinion) the shininess of 4th Edition had moved further away from: the feel that these spells were part of some imperfect reality, perhaps, in some cases, kludges or "panda's thumbs".
Well, these "Behind the Spells" give us all of that back. I've read six pages on the history and qualities of dispel magic, and it feels more "real" to me. These 38 spells are going to be drawn up into a hardcopy book, and I'm going to loan it to the people who play Wizards in my campaign and say, "Write something like this for a couple more of your known spells."
Wizards should know this kind of trivia about their spells. (Sorcerers, or rogues reading scrolls, not so much.)
Why only 3 stars? Most of this 6 pages is backstory, and it could have been summed up in a page, and the back-story may not fit everybody's campaign.