We have run focus groups on characters such as how cool they look, what special powers they have, and how they are dressed. There are interesting differences between Asia and the United States in terms of preferences for character design. So it is important to do these types of tests in your major target markets with a large enough sample size.
Beyond aesthetics, I think it is equally if not more important to get feedback on a character interaction-how it feels to be that character. Game characters are a very important part of the player experience and require special attention during testing. Frequently, character action and motion requires such a steep learning curve that many players stop. That’s what makes Grand Theft Auto and Katamari Damacy so easy to start and play. You don’t have to be that good at the controller to have fun. Simply providing “appealing” characters doesn’t guarantee engagement. One game concept turned a first-person game into a third-person experience. Even though the characters could be customized to look like the player, this wasn’t how they liked playing. You have to make sure the experience of being that character provides the type of fun that your audience wants.