I use mine with the $39 case. The $59 (third party) case offers more viewing angles but I simply find things on the table to prop it to the desired angle and use the device in portrait mode with the flap folded over the back. When I want to type, I resort to Commodore 64 mode where the device is in landscape mode with the case folded such that it props up the device about 15 degrees.
The case offers you a more "book like" thing to hold onto. Without the case, I think the iPad might be slippery and "giant iPod Touch"-like. The case does add a small amount of weight but it is worth it to me.