In brightly lit rooms, especially with bright overhead lights, it can be really distracting. Outdoors in sunlight it is mostly unusable. In the proper lighting where no light fixtures are reflected on the screen it is wonderful. Some people like using a non-glare screen protector and find that it helps. In my experience the non-glare screen protector I tried made the text harder to read. Even in perfect lighting, the iPad will not render text as well as the iPhone 4 are the eInk readers.

If the lighting is good then I can read for hours. If there are reflections on the screen, then I have problems after a short period of time.

I mostly read on mine and I leave WiFi on. I estimate about 10 hours on a battery charge using my conditions. However, I usually have the screen turned down to around 30%.

I love the iPad for the ease and speed of highlighting, looking up words in a dictionary, annotations, etc. All of these functions are excrutiatingly slow on most eInk readers, not to mention clunky due to eInk inerfaces. But here is what I normally wind up doing: Any outdoor reading is done on my eInk. Most bright area (brightly lit room) reading is usually done on my eInk. All dimly lit area reading is done on my iPad or nookcolor. I prefer the iPad over the nookcolor because the nookcolor is not as easy to operate and the touch screen is not as sensitive.