The Xbox 360 can be positioned both horizontally and vertically and this is entirely your choice. However, when placed vertically it is obviously susceptible to being knocked over. This will not only damage the console itself both internally and externally (scratches) but also if it is on and a disc is inside, your disc will get scratched with what are called "Halo scratches".
This is where rings of scratches appear on the disc and you may not be able to play certain levels or maps on a game. This is why the Madrics Freezer stand is so helpful. It adds a great deal of support to the 360 when vertical and reduces the chances of it being knocked over and causing further problems.
In addition, it also has fans to stop the console from overheating. Xbox 360's are notorious for the Red Ring Of Death so these fans will aid substantially in preventing the 360 from rising in temperature too much and will keep your console running, especially if you play for prolonged periods of time.
Lastly, the stand looks great. It makes the console look smart and also matches the colours like all other accessories for the Xbox 360.