Rather than looking for the user Interface for a sports betting site, I would rather like to see the odds they provide and how reputed is the site. That's my personal choice and other people's opinion may differ.

Unless the user interface is extremely poor or lagging, I would avoid that site but when I need to choose I will compare the odds between different sports sites and gamble at the site that offers the best odds. Maybe I can compromise the user interface but go for a better odds. The reason is that the main goal of sports betting should be to win and when you bet on good odds your percentage of amount winning also increases.