How does it compare to his elder brother? ( Blade 3 ). The design at the bottom looks a bit different. I've also asked the salesperson what is the different, most of them just said that the latest version is always much better than previous 1. So I wonder what is the different between this 2? And also, I would like to get some reviews of it before buying it. I just missed the Blade 3 cause Blade 4 has already launched.