Looking for iPhoto... that is just Mission Control.
Looking for a finder window? On SL it would be hard to tell which finder window was the one you wanted without looking closely or hovering the mouse. In Lion you can Mission Control-->Finder-->App Expose Now you are only looking at three windows that are much bigger on the screen than in SL Expose. A much more manageable solution IMO.
Looking for a minimised application? That is... oh... I guess I will have to right click on the application icon and find the specific window that was hidden. Of course I will then have to identify it by the title of the window and not what it looks like. I understand that you can use app expose but it takes longer to select the application and then activate app expose. Of course you can get them to show in the dock but I personally do not like that setting.
What happens if I minimise all windows in an application and want to access just one of them? As soon as I select the application to activate app expose, it would make one of the windows appear and probably the one I don't want, so I will have to show the window I want and then go back to the other one and hide it.
Mission control is good but so is expose. It would be great to get the best of both worlds. It would be great to have Mission Control similar to how it is now but make it possible to see minimised windows and make it so that expanding a stack of windows in an application can be done simply as if it activated app expose and not simply spreading them out a bit.