Even without using full screen mode the multi display support is passable at best. There is no way to turn off any of the connected displays, which is a problem when giving presentations or even when just connecting my mac to the TV so we can watch a film with friends - mac's display needs to stay on, there is no way to turn it off.
Yes they will, except that they will automatically enter sleep unless they are plugged in, which is not always the case. And I am not going to change my power settings to not sleep with the lid closed just so I can turn the display off - it's daft, there should be an option to do that in the displays menu. And even if you turn the brightness all the way down the display is still active, it's just the backlight that is off.
This is a good point, but doesn't seem to be like a very big one. (I'd like to be able to turn off my tablet display when I'm not using it.)
It seems to me that Apple's emphasis has been on using one screen well and applications like FCPX that use privileged APIs to use fullscreen well across monitors, but developers who use multiple displays in more complicated ways are pretty much stuck with third party solutions (I use SizeUp, and I used to use Cinch). This doesn't solve the issue you mention, but I'm very happy with it otherwise -- and when Apple incorporates the features of nice third-party utilities into the OS it gets lambasted from the other side.
