It seems like the main advantage of the Surface will be Windows 8's ability to be used both as a mobile OS and as a desktop OS. In your case, Android doesn't let you run unported Linux programs and Debian, if you booted into it, wouldn't support touching the screen. If the Linux kernel supported the Transformer Prime's touchscreen, and if a touchable lightweight window manager were designed for mobile use, and if the Android emulator for Linux were much faster than it currently is, let's say by using full-speed virtualization or something, a tablet/laptop combo like the Transformer Prime would be the perfect computing device for me.

Mac OS X 10.7 and the future 10.8 are converging on iOS's UI, and I wouldn't be surprised if 10.9 or Mac OS 11 or Mac iOS or w/e the next Apple OS will be called will run on desktops and mobile devices. If so, it will be interesting to see if they merge the iPad and the MacBook Air into a Transformer Prime equivalent that has a full OS. If the Microsoft Surface becomes popular, maybe they'd even rush to do this under Mountain Lion and provide an iOS emulator/virtualizer or something. I get the feeling this will happen sooner than Linux meeting my above-stated requirements, but I'm optimistic that there will soon be at least one alternative to the Surface that runs something more powerful than Android