I suggest giving the Kindle app a trial period, then deciding based on your preferences and uses. There are plenty of readers who've given up their Kindles in favor of iPad and other devices, but it's based on what works best for the individual.
I started off with a Kindle several years ago, because I don't watch TV or play games, and reading is my primary entertainment. But I've not used my Kindle at all since I got my iPad 1 more than a year ago. I even brought my Kindle to China for several months and ended up not using it at all. I haven't brought it on trips since.
I don't bother reselling stuff, so I still have my Kindle. I figure if some natural disaster strikes and I lose electricity for an extended period, I can fall back on it. I just have to remember to keep it charged. It holds a charge well, so I charge it every other month or so.