It's not great for board books (we have a few in there, but they take up a lot of room), but it's awesome for skinny picture books. I just counted, and there are forty books in there. They have a lot more than forty books, but the rest can live on a bookshelf in another room and get circulated in and out as desired. I just set this all up yesterday, so we have yet to test whether it actually gets them reading books more often as a default option, but I am hopeful!
It's not super-cheap, sadly, at $85. The internet has a lot of DIY versions, if you are handy (google 'book sling'). But if you want to just get up and go, this is the one we got.
I had some thoughts that I would paint the natural sides, and/or change the fabric, but by the time I actually get around to doing that, the kids will probably be done with picture books. :-)