The features I used were it would add a button to the windows you could click that would send that window to the other monitor.

Also ultramon lets you use one image as a wallpaper on both screens. Like I have mine set to 1600 x 1200 so I could use a 3200 x 1200 image across both screens. I know I can just cut the image in half and stick one half on each monitor but it would be nice not to have to do that.