Higher frame rates are typically only good for one thing; slowing down the motion in post production editing. It's good for faster moving objects as well for smoother motion, but 30 fps shouldn't give you any issues for 99% of things out there that you are videoing.
As long as you're at 24 fps or higher, you're getting smooth motion in real-time video.
There are a lot of factors that go into the quality of the video that is being taken, and the poster above did a great job of explaining it.