Previous commenters have already covered the good points. It's a compact and convenient way to store large numbers of discs. A few things to watch out for, though:
1) Build quality is good, but the sleeves hang by a hooked plastic bar from rails and the design doesn't feel very secure. Fine for storage, but if you're using it for transport I suspect you'll need to be careful to keep it level and avoid knocks, or everything's going to go flying inside.
2) The bars/rails design means that normal disc sleeve refills aren't going to work - they don't have the bars - and despite Mr. Digweed's comment I can't find matching refills available for sale anywhere on the web.
3) The "800 capacity" is a bit misleading; it assumes two discs per sleeve, back to back. The big benefit of this kind of storage - as opposed to the more common book-style wallet - is that you can insert a new disc without having to shuffle everything else along. Packing two discs per sleeve kind of negates that. (And if you aren't storing alphabetically, good luck finding anything, especially if half the discs are facing away from you.)