I bought my 10yo daughter a nice road bike, a specialized dolce vita, and she got on it and rode. She'd never been on a road bike before. It took one loop around the park and she was shifting like a pro. While she isn't going to win any races yet, she really does ride well. Her twin sister is a few inches shorter, too short for a full size, if small framed, bike and won't ride with us anymore because she just can't keep up. Maybe next year for her.
In any case, just get the bike YOU want, not what some salesman says. Find yourself a good shop too.