As for actual content, I can't say it's very interesting for fans who already own all her studio albums. However, it LOOKS fantastic, especially in the pictures where it's all opened and the contents are spread around. I might have to get one when I have some money to spare, even though it's mainly the packaging, the TA Live DVD, and "Mirrorcle World" that interests me. I can't help thinking that this would have been 100% better if it were an actual singles box set, as in packing every single-released track, b-side, and remix as they were originally released in one big multi-disc set (each album could probably have its own disc to save space). That'd be appallingly expensive, though.
Oh, and just like everyone's been saying, this makes A BEST 2 completely useless. I'm really glad I didn't buy that.