Now you can use Alt key, which is used rarely, as modifier. However, if you do use Alt as modifier, holding it will not be triggered any more, even you configured it; and of course Alt+Alt means nothing.
Since it has to wait and check for key hold, a key down won't be triggered until you release it, therefore you may have noticed the letter now comes out on key-up while you are typing. This won't slow your input speed, but still you have the choice to configure KeyLauncher disabled on input, or you just don't setup any key holding launches.
If you have Accessorizer installed (you should), you can launch applications on top of another (like a DA) without quitting it.
Also, A lot of UI improvements included.