If you've been paying even the slightest bit of attention to the tech world for the past year or two, you're probably well aware that Android has more or less taken over the smartphone scene. Way back in June of 2010, Google revealed that 160,000 Android devices were being activated per day - at the time, that was more than double the combined total of iPhone, Mac, and iPad activations.
One of the reasons I love Android is because you can customize the heck out of your experience. Replacing the stock launcher with Launcher Pro is pretty much the first thing I do now when I get a new phone because of the innovations a hard-working, smart, and dedicated engineer (Fede) can bring to the table.
However, Launcher Pro is not too much different from the stock UI, outside of tweaks and other little but important things - same goes for ADW and other home replacements.