Battery life
Battery life on portable ebook readers is typically defined by manufacturers as page flips or page turns, meaning how many electronic pages a reader can display before the device needs to be charged. The general idea here is you want to have at least a week or so of battery life with other features turned off, or several thousand page turns.Storage capacity
Most ebook readers offer internal memory to let you store hundreds of books, while other readers allow you to insert memory cards so you can store as many ebooks as the card has available memory for. Some readers even offer a combination of these options. The general rule of thumb is the more memory, the better.Screen size
Screen size is important to consider, unless you don't mind squinting to read text on a display no larger then that of what is on a typical cell phone. The larger, the better is the what you want to shoot for. Keep in mind, though, that larger screen sizes also impact how portable the ebook reader is. You might also consider readers which offer adjustable text sizes on-screen.Navigation controls
How do you plan to handle your ebook reader? One handed while drinking a cup of coffee with the other? Navigation controls, properly placed on the reader's external casing, can allow this choice to be a consideration. These controls will let you change pages, change book selections and access other reader features.Dimensions
An ebook reader, to be truly portable, must be very thin and very lightweight. It can have a larger screen size, if possible, but should also remain very slim at the same time. Lugging around something the size and weight of an encyclopedia defeats the purpose of being able to carry lots of your favorite books in digital form.Ebook offerings & delivery method
Some ebook readers let you read PDF files, while others only work with special formats created by the manufacturer. You'll typically find more mainstream book titles, due to copyright issues, leaning towards these special - and typically more secure - options. Public domain books, meanwhile, might be available in PDF.Also, do you have to load the books into the reader's memory through special software, or can you buy and download them directly? Directly would seem better, but it could add to the cost of the reader due to the wireless technology needed to pull this function off.