My iPad2 gets daily use, 12-16 hours every day. It is over 3 years old and is showing no signs of battery deterioration. I intend to use it until it fails completely, so watch this space. When batteries do fail, make an appointment at the Genius Bar. They can be replaced, but only by people who know what they are doing.
Agreed. Battery replacement for the iPad is $99 bucks, I believe which isn't so bad. If you have a good device then it's worth investing a hundred bucks to do it. If it's a really old device and close to be outdated then I'd skip it.