Hrm. I was really hoping for something more like a comic with this book, or perhaps like a picture book. Something with a bit of plot. This is just a summary of the series, with a somewhat deceptive title. After all, if you see a book cover of Aang and Tenzin, with the title "Legacy," you think we;re going to get more involvement with Tenzin, but this is basically a scrapbook.
If you want to learn more about Avatar, fine, but you're not going to learn much more than what's in the original series. Really you'd be better off getting the comics than this book. And if you're looking for an Avatar-related gift, I'll tell you right now, get the comics! This will be a huge disappointment.
For the individual, unless you're a rabid collector, pass on this. See if your local library has a copy, if you really want to read, but pick something else to purchase if you really need some Avatar on your shelf.