I found the design to be pretty confused, and I suspect that most visitors will leave immediately because of this. You need to communicate what the site is useful for, and how to start using it simply. For example, I wasn't sure whether to start by searching for an item, or clicking the 'Start KartMe' button on the right.

Maybe the design mirrors the fact that the site is trying to do quite a lot of stuff. It's a pretty impressive feat technology/coding-wise, but it might be worth tweaking the homepage (and maybe moving some stuff off it) to help ease the new-user experience.