Robin is easily the most recognizable of the Teen Titans, which is no doubt because of his legendary heritage as Batman's sidekick. This version is Dick Grayson, the first Robin, and though we don't see Batman in the series, we do see his influence on Robin throughout.
What's also interesting is that he didn't mean for this team to happen. He was trying to go solo, but certain events led him to meeting the other team members, and thus the Titans were formed.
Robin believes in discipline, but also cares deeply for the team. He's hot-tempered at times, but is also cool under pressure more often than not. And despite not having any powers, he's a force to be reckoned with at all times.
What made the cartoon so great for the character was that it wasn't afraid to push Robin to dark places in order to get certain missions done, a very Batman kind of thing, and it worked. But it also worked in the more calm and subtle moments where Dick Grayson was able to show up more than Robin.