Some people are too lazy to scroll through a whole profile, so the "About" section is your chance to grab their attention. Give people a short summary of who you are, what you do, and where you've worked. It's also a good idea to include your contact information here as well. And yes, some of this information will be repetitive and repeated further down in your profile, but again, not everyone is going to take the time to scroll down and read that. Give people the key information straight from the start.