Heres a comparison of normal maps at different ranges. Bear in mind that the i created a lazy texture to normal map type map, custom normal maps from high poly models will be much better.
(http://img805.imageshack.us/img805/4215/nmappic.jpg) (http://imageshack.us/photo/my-images/805/nmappic.jpg/)
It seems that normals maps are subtly visible at medium ranges (about the default range), but very noticeable when up close to units.