| save the trees, stop using hardcopies. There are so many level editors, it's only good that they don't come with a paper manual. Imagine brasil would look like arizona.|
A level editor should have context sensitive onscreen help, probably tooltips. I should be an intuitive Interface. So you probably won't need to read more than two pages of a text file.
So if I was you, I wouldn't rate the presence of a manual that heavy. You'd probably miss a lot of good Apps. Although, halos tool may be pretty good.