For starters, mini laptops have less powerful processors, the Intel Atom mostly. This will give you basic processing power, and great battery life. You cannot play any good games, graphics design will be painfully slow (excluding the issue of the tiny screen). The screen resolution does not support Windows 8 Metro apps, not really a big deal, but still, you'll miss out on some of the cool eye candy of Windows 8(.1).
My advice: Rather buy a Windows Tablet if you want a small windows computer, or just buy a normal laptop.