I find it fascinating how many chat applications exist, and how success is almost completely due to design. Most chat features you find in newer chat apps, like Kik or Whatsapp existed since AIM. Yet users are very willing to jump ship and grab onto an application with the same, perhaps fewer, feature if it's more eye-catching, or intuitive. It's a nice reminder that part of innovation in the tech industry is UI, and if you innovate a new interface for an existing service, it can be as ground-breaking as any other innovation in the industry.