I find that using a Bluetooth keyboard allows me to work much faster with my iOS devices, both when typing and when controlling Voiceover with QuickNav. When I purchased my third generation iPad, I looked at and tested several keyboard cases, by far, I found the ZAGGfolio keyboard case (made by SAGG) to be the best one!
Externally, the case is covered in either carbon fiber or leather (which is slightly more expensive), and comes in a variety of colors. The texture is pleasing to touch and it isn't slippery, so you are not likely to accidentally drop it. The case closes securely and it supports iPad's magnetic lock/unlock function, so your iPad will automatically go to sleep when closing the case. Holes on the sides of the case allow for easy access to iPad's buttons and connecting ports.
The real goodies, however, are inside! The case includes a full and very well constructed Bluetooth keyboard to be used with your iPad in the same way as an Apple Wireless Keyboard (please refer to the Apple Wireless Keyboard reviews already posted on this site for instructions on how to connect and use the keyboard with your iPad). A feature of this case's keyboard that I find is very important to me as a visually impaired user is that the up, down, left and right arrow keys are nicely isolated on the keyboard's lower right corner, making them very easy to locate. The arrows on other case keyboards are often buried between other keys and not marked or differentiated in any way. The keyboard features a complete set of keys; on other case keyboards you sometimes have to use a function key to access special characters such as question marks or hyphens. The top row of keys allows you to quickly access a variety of functions, such as volume, Spotlight Search, Play/Pause, etc. The key on the top left corner functions as the iPad's Home button, while the one on the top right corner functions as the iPad's sleep/wake button, therefore, if you wish, you can entirely control your iPad without ever touching it, even turn it off. For those who type in several languages, like myself, the key on the lower left corner quickly changes your keyboard and input language (to do this, you first must select the languages you want to use in Settings > General > Keyboard). The keyboard's on/off switch and pairing button are easy to locate and use without seeing them. The keyboard's battery lasts for about two months with moderate daily use and charges in two to three hours. If you wish, you can take the keyboard and your iPad out of the case to use them, but this is not necessary, you can just open the case and place your iPad in a vertical position, which locks down quite securely.
I would only like to mention two aspects of this keyboard case which could be improved, but they are not relevant enough to discourage you from considering it. (1) To charge the keyboard, you must first remove it from the case; the charging cable cannot be connected when the keyboard is inside the case. (2) Your iPad can only be used in landscape orientation while inside the case; you need to pull it out to use it in portrait mode. Despite these two drawbacks, I am giving this case a five star rating, simply because I believe that no other case better serves the needs of blind and low vision users. It's price is very reasonable too, $99.99 USD, I highly recommend it!