Live Tiles are a great concept, but people were complaining that their positioning and size are too rigid, and Redmond listened! Gone are the days when you place a few of the limited choice of tiles, and they take up the whole homescreen.
A new tile size is introduced, that takes a quarter of the screen's width, and tile size to use is now up to the phone owner. By long-pressing a tile you can choose three different sizes - quarter, half and full width.
Now you can add, remove, replace, resize and basically do anything with the new Live Tiles that your heart desires. This is comparable with Android's resizable widgets, and makes Windows Phone the next mobile OS where you can completely customize your user experience on the homescreen, so you get to rarely even visit the app launcher menu.