The main improvement of the second generation Apple TV is the shape and the design, which is much better and a lot smaller. You will not even notice the little square metal brushed box standing next to the TV set. The next very important improvement of this device is the fact that it has now a larger storage capacity, advancing from the first models that had 40 GB hard drive up to 160 GB at your disposal. You now have the possibility to store lots of videos and movies and everything you might care to watch on this big capacity hard drive.

It is very useful when you want to watch a certain movie and you no longer have to start looking for it, as you don't have it on your device. This new version appeared only months after the first version of the device was released on the market, that is it appeared on May 31, 2007. Of course a better version meant better sales, but that applied mainly to the second generation Apple Tv, and that is why Apple management decided to discontinue the cheaper model that had only 40 GB hard drive capacity.
Because the first models of Apple tv were not compatible with HD tv screens, the images were distorted and somehow unnatural if you connected the device to a HD tv set. This shortcoming was corrected and now you have the possibility to adjust the image according to the type of screen of your TV set. If you want to know more detailed about this device, you can always visit the official Apple web site or the web page hosted by Wikipedia, that describes it in details or you can read the following reviews: www.sfgate.com and www.bindapple.com.

My opinion is that it's a pretty great device, but I am not sure that it will be able to survive on the market because now you have access to a lot more sophisticated devices that can do its tasks without having to be bound to one place, but portable and taking less space, too. But I think only time will tell if I am right or wrong.