I've rooted all my devices now. It's perfectly harmless most of the time, especially with the more popular devices. There's walkthroughs and tools all over the place to help you through. It doesn't really help battery life just rooting it though. But once it's rooted you then have the ability to take off all the bloatware (not by default however, sometimes certain apps can help remove unwanted apps, other times you have to acquire a custom version of your firmware that doesn't have those apps with it. This wipes out everything and you have to re-download all your apps)

More powerful devices rarely need to be rooted anymore. But there's no real reason not to root either. It's handy if you want to install an ad-blocking app and stuff. And it really helps file managers and virus scanners to have root access too